On this page:
The refrigerator used on the Rialta probably accounts for the
most customer complaints of all appliances and devices installed in the vehicle.
Lots of these complaints are caused by "operator error" or not really knowing
how the thing works.
Winnebago installs a
Norcold refrigerator in every
Rialta and every model is capable of running on three different power sources:
propane (LPG), 12 VDC, or 110 VAC.
||The Model 22QD and 22FD both
get the Norcold 3163 series which is a single door model with 1.8 cubic
foot interior volume. The RC and RD, and possibly some of the early FD and QD had the N260.3 model with 2.4 cubic feet of interior.
|The Rialta Model 22HD get
a slightly larger model with a freezer, the Norcold N300.3 which has 2.7 cubic
foot interior volume.
Although you have 3-way power to choose from, each one has its
intended purposes while traveling.
The AC Mode of operation should be chosen when you
have a shoreline connection either at home or at campsites that can provide
110 VAC power. If the vehicle is in motion and for some reason the 12 VDC mode
is not functioning, then running the generator to maintain refrigerator operation
may be needed.
The LP Mode of operation should be chosen while the
vehicle is stationary and there is no source for continued 110 VAC operation.
The amount of LP consumed by the refrigerator is miniscule compared to the consumption
by the furnace during cold weather. You should not use LP operation while the
vehicle is in motion because most local, state, and Federal regulations prohibit
its use, and usually the air currents generated by the motion usually prevent
proper heating action. Although some people report that they have been able
to accomplish the feat.
The DC Mode is intended only for use while driving.
While in this mode, the unit operates without thermostatic control. For those
willing to modify the internal wiring (and void any existing warranty), there
modification available which will allow for thermostatic control in this
When preparing for a trip, do NOT use the DC mode for the initial cool down
of the refrigerator but instead use either AC or propane. It should normally take
at least three hours or more to cool down the refrigerator BEFORE any food is
placed into it.
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All links to files in Adobe PDF format.
Norcold Model N300 (Rialta HD):
& Owner's Manual (990k)
Service Manual (830k)
Service Bulletin - Checking for problems in LP mode (101k)
Norcold Model 3163 (EuroVan Camper and Rialta FD and QD)
& Owner's Manual (596k)
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General information and may not apply to all models.
Do I have to manually start a pilot light for LP operation?
Technically speaking, yes. But you don't need a match. The
initial spark is provided by the piezo igniter that occurs when you push the
button repeated on the front control panel. (N300 only)
How level must my refrigerator be?
The refrigerator is made to operate within 3 degrees off level
side-to-side and 6 degrees off level front-to-back (looking at the front of
the refrigerator). For an informative and complete description of what this
looks like in the real world, read "How Level
Why is frost on the interior cooling fins only on the right side?
It is normal to accumulate frost on the right side of the
bank of cooling fins. The coldest part of the cooling fins are those on the
right side of the refrigerator as viewed from the front. Gas/Electric refrigerators
will build frost of varying amounts depending upon the environmental conditions
(temperature and humidity), how often the doors are opened, and what is stored
in them. Defrosting is not required until a decline in performance is noted.
Refer to your operator's guide: "Defrosting and Cleaning the Refrigerator Interior."
Does the refrigerator perform better on gas or electric?
The refrigerator is designed to operate efficiently on both
gas and AC electric. The AC electric is dependent upon the AC input voltage
to the refrigerator. Be sure that the input voltage is between 108 volts AC
and 132 volts AC. The efficiency of the refrigerator while operating in the
gas mode is dependent upon the correct burner flame. The burner flame requires
correct input gas supply pressure, air input, and burner and burner orifice
cleanliness. Refer to the refrigerator's operators guide: "Refrigerator Maintenance
and Care List."
Does a fan installed on the back of the refrigerator help performance?
A DC fan may help improve refrigerator performance when the
refrigerator is not installed in accordance with Norcold's installation requirements
or when operating the refrigerator in high ambient temperatures (see "Refrigerator
Installation Manual.") A DC fan will assist in providing the necessary amount
of airflow. Be sure the fan is controlled by a thermostat and begins to operate
when the area behind the refrigerator reaches approximately 95 degrees F. The
fan should run until the temperature lowers to about 80 degrees F. Consult with
your RV dealer for the correct fan and specifications.
What maintenance should be performed on my refrigerator and how often?
Your refrigerator will give you years of trouble free service
if you do the following simple checks every three to six months. Refer to the
operator's guide provided with your refrigerator for more details:
► Keep the food compartment and the freezer clean. See "Defrosting
► Defrost the refrigerator as necessary.
See "Defrosting and Cleaning."
► Make sure the door seals correctly. See "Door Sealing."
► Be aware of any cooling changes that are not because of weather,
loading, or gas control changes. If changes occur, contact your dealer or service
► Make sure the gas supply is LP gas only and not butane or a
► When in LP gas operation, examine
the appearance of the flame. See "Gas Flame Appearance."
► Make sure the air flow in the lower intake vent, through the
refrigerator coils and condenser, and out the upper exhaust vent is not blocked
► Make sure the area behind the refrigerator
is clear. Do not use the area behind the refrigerator for storage of any combustible
materials, especially gasoline and other flammable vapors and liquids.
How do I remove the wire shelves inside the cabinet?
The refrigerator shelves are secured with either clips or
shelf retainer strips. Refer to your refrigerator's operator's guide, provided
with the refrigerator, for removal procedures.
Why does it require 12vdc to operate when using LP gas?
A 12-volt DC supply voltage is required to maintain the refrigerator's
operating control function on some models, such as the 3163, and the refrigerator's interior light. It is NOT needed
for the model N300.3
How long should it take to get cold after it is started?
On initial start-up, allow the refrigerator to cool between
8-12 hours before loading it with food. Warm foods, high ambient temperatures
and frequent door openings will increase the cool down time.
What is the cause of my refrigerator having an ammonia smell?
An ammonia odor detected inside the refrigerator cabinet or
at the rear of the refrigerator indicates the cooling unit has developed a leak
and requires replacement by your dealer or an authorized Norcold service center.
Remember, you are dealing with a complex appliance that operates on both LP
gas and electrical power. Servicing this unit should only be done by a trained
technician to avoid potential dangerous consequences!
Is my refrigerator self-defrosting?
No. Your refrigerator, unlike a home refrigerator, is not
equipped with a heater that automatically eliminates the need for defrosting.
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Leveling the Refrigerator:
Winnebago's Rialta Operator's Manual for the Norcold Refrigerator
says "operational limits of 3 degrees off-level side-to-side and 6 degrees off-level
front-to-back". Are they describing the vehicle or the refrigerator?
Its not immediately clear but an additional paragraph farther
down the page states "6 degrees front-to-rear (such as steep driveways...)" which
sounds as if they mean that "front-to-back" relates only to the vehicle. At best,
this is misleading; at worst, it is incorrect. It actually depends upon which
model of Rialta you own, but the language in the Winnebago manual does not make
The Norcold manual itself is very clear and definitive: it defines
the condition "as looking at the front of the refrigerator". This makes a difference
because in two Rialta models, the refrigerator is mounted sideways inside the
vehicle (HD and FD) while the third model (QD) has it mounted facing straight
The Real World:
OK, now that we know just how much out-of-level tolerance is
allowed and in which direction it is measures, what does this look like in the
real world when you are parked on uneven surfaces? There are two places where
you can visualize or measure this tolerance:
At the wheels themselves, since this is where you actually
shim to make things level. You don't shim the refrigerator, or if you do, then
you're doing things the hard way.
At the flat counter-top immediately above the refrigerator
using a small 24" long bubble-spirit level.
Notice that I did not include that miniature round bubble-in-a-circle
level that is given free from a lot of RV dealers or comes free with the refrigerator.
Using such a small level, it is difficult to determine which wheel needs to be
shimmed and furthermore, it is in-expensively made and not very accurate.
Let's first take a look at the wheels and visualize the maximum
allowed variances which would still allow the refrigerator to operate properly.
We need to look at two scenarios because the HD and FD are mounted sideways, while
the QD is facing straight forward.
After viewing the sketches, it is apparent that
the refrigerator is supposed to work properly well beyond what we all thought were
the limits for out-of-level condition. And after viewing those sketches, you are
probably asking yourself "Why bother leveling at all?" Well, the answer is simple
and Winnebago has its entirely correct with this statement from the Rialta's Operator's
Manual, "Normal vehicle leveling to provide comfort for the occupants is
satisfactory for refrigerator operation".
It's apparent that you seldom really need to level the vehicle
in order to make the refrigerator operational. In fact, most of the time the reason
to level the vehicle is so that the occupants feel more comfortable. I, for one,
can not sleep in a bed that is tilted sideways even the smallest amount. Somehow
my internal "human level" will tell me if its within tolerance.
There are some owners that will use jacks stands to help stabilize
the vehicle from rocking and at the same time help bring the vehicle into level
without using blocks underneath the wheels. This makes lots of sense especially
if the vehicle is going to be in the same position for more than just overnight.
However, given the fact that the refrigerator can operate properly at angles we
thought prohibitive, those people who are using the plastic or wood blocks to
raise one or more wheels by only an inch or two are hopefully doing so for their
own personal comfort, and not for the refrigerator.
The bottom line is this: "Just how sensitive are YOU to being
slightly out of level?" If it doesn't bother you, than you may never have to level
the vehicle unless you are parked on some extreme gradient.
Now that you've read all of this and practice
it a few times in a campground or out in the boondocks, you'll probably find out
just what works and what doesn't work. You'll end up taking a glance at that cheap
round bubble-in-a-circle level and after doing a quick check of your surroundings,
you'll say "Close enough!! Let's eat!!"
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Leveling For The Geek:
Now let's look at a real world solution that
you can use to making those adjustments in order to "feel comfortable".
All you need is a 24" long level easily obtained at any hardware store for under
$10. I chose the 24" length because it will provide you a measurable variance
that you can easily see. And it will easily store in the nearby overhead cabinets.
The use of any shorter level means that an error in measuring of 1/16" can easily
translate into one full inch at the wheels.
Here's how to determine you vehicle's level
from inside the vehicle. Stand facing the front of your refrigerator and place
the 24" long level on the flat counter above the refrigerator. You will need to
check straight forward and sideways. It's as easy as 1-2-3:
- Lift one end of the level until the bubble is centered.
- Measure how far you had to raise that one end of the level.
- Compare that measurement to these sketches.
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Maintenance & Cleaning
Very little maintenance is required of the refrigerator. Other
than the cosmetic cleaning of the interior plastic, there is little else required
for the normal operation of the refrigerator. The operator's manual notes that
the unit is NOT self-defrosting so if over an extended period of constant usage
you find frost build-up to be a problem (rare for the average RVer), then you
will need to manually defrost the unit by simply turning it off, removing all
food, and waiting for all accumulated ice to melt. In the meanwhile, you will
need to soak up the water with towels. The operator's manual also suggests the
use of a solution of liquid dish detergent and warm water to clean the refrigerator
right after defrosting. Do not use abrasive cleaners, chemicals, or scouring pads
because they can damage the interior of the refrigerator.
If you are considering doing a thorough cleaning of the entire
heating portion of the system, then refer to the "Replacing
The Thermocouple" section on this page as this details the steps necessary
to remove the refrigerator and shows the additional cleaning of the heating elements
and other related parts.
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N300 shown. 3163 is similar, but has different parts.
The Norcold Operator's and Installation Manuals recommend that
any of the following service procedures on the refrigerator should be performed
by a qualified RV dealer or a Norcold authorized service center.
With that being said, I've usually heard that many RVers have
had to take their rig back several times because the problem with the refrigerator
was not fixed right the first time. And I've seen the caliber of many workers
at these RV dealers and quite frankly, I'm surprised that they manage to fix anything
at all. Even when my Rialta was brand new, it would not run on propane and it
required three trips to the dealership until they finally got it right. On the
last trip to the dealer, I told the service manager to fix the problem and leave
the unit running on propane so that when I went back to pick it up, I could then
immediately verify if it was going to work or not.
I must also state that if your problem includes the smell of
leaking propane or ammonia gas, that you immediately shut off the propane tank
and seek out qualified help in determining the cause of the leak. Do not travel
in or occupy a coach when you can smell propane or ammonia gas.
Electrical Operation (12 VDC & 120 VAC):
Usually either of the two electrical modes of running the refrigeration
unit are problem free. The unit either gets power to heat up the ammonia gases
to work properly, or it doesn't. Norcold stipulates the requirement for AC voltage
as between 108-132 volts. The requirement for DC voltage is between 11.5-15.4
volts. These voltages should be measured at the refrigerator's power terminal
block on the back of the refrigerator. There are two fuses located near the electrical
terminal block in the wires that run to either of the 150W DC heater or the 180W
AC heater. The AC holds a 3 AMP fuse while the DC line holds a 20 AMP fuse. These
are glass fuses so a visual check or a continuity tester can verify the integrity
of the fuse element. Make sure that the propane tank valve is closed while doing
any checking of electrical contacts.
Propane Gas Operation:
This is the mode of operation that causes almost all of the
problems associated with the function of the refrigerator. There is one rule to
remember about troubleshooting any propane related issues with the refrigerator:
"cleanliness is next to godliness". Nearly all of the problems will generally
occur within the burner box area. My information presented here also assumes that
the gas control valve and safety valve function normally. There have been very
few reports of any problems with these items.
If you are experiencing problems running under propane, then
some housecleaning of the burner box will be needed. Many people have reported
that simply cleaning out accumulated dirt, soot, spider webs, etc, was all that
was necessary to remedy their problems. I personally find this a little implausible
because I believe that most of the problems are related to a dirty, contaminated
thermocouple or a clogged and dirty burner orifice. These items can
not be cleaned without removing them from the burner box area.
If the gas seems to ignite with no problems but the flame extinguishes
as soon as your release the button on the control panel, then that signifies a
dirty thermocouple. If you have problems even getting the flame to initially ignite,
then that signifies a problem with the burner orifice or maybe the igniter.
So how does one tell for sure if the gas is igniting or if
the flame extinguishes? The answer is simple: you need two people. One
to operate the controls on the inside of the coach while the other observes the
action of the flame. First remove the outside lower vent cover. In order to fully
see the flame, one needs to remove the burner box cover. It is held in place with
one screw. It also helps if this work is done in the shade or in a well ventilated
covered area otherwise bright sunlight will hamper one from seeing the flame.
Remember, this is a VERY SMALL flame, much like nothing more than a pilot light.
This is NOT a wide, large flame that you'd see on a furnace or stove. See Photos
#3 and #6 below for examples.
Remove the one screw that holds burner box cover in place.
Photo #2 below shows the complete burner box with the cover removed. Note the
dirt and debris laying at the bottom of and all around the burner box. Actually
this one is fairly clean; yours may be much worse. The red wire is the igniter
lead; the thin copper tube is the thermocouple; and the brass fittings are part
of the propane gas line and burner orifice tube. These are the three items to
be checked and cleaned.
- Open the valve on the propane tank.
- Turn the thermostat to its coldest or highest setting.
- Turn the selector switch on the control panel to the gas position
Push and hold the safety valve button in the fully depressed
(NOTE - This "safety valve" only allows gas to flow when there is a flame present
or when the button is pressed. Any loss of flame as sensed by the thermocouple
closes the safety valve and stops the flow of gas. The button that you push in
and hold from the control panel actually bypasses this safety function and causes
gas to flow as long as you hold in on the button.)
- In rapid succession, push the igniter button several times for about 5 seconds.
While the person on the inside continues to hold in the safety
valve button, the second person who is trying to observe the flame inside the
burner box should be able to see a bright blue flame at the end of the burner
No flame at all: double check to make sure the valve on the
propane tank is open and that the manual valve on the back of the refrigerator
is also open. This manual valve should always remain in the ON position. If
you can smell propane but there still is no flame, then you probably have a
faulty igniter or else the burner orifice can be fully clogged.
Flame present but it is yellow instead of blue or else the
flame flickers erratically: you probably have a clogged burner orifice tube
which needs to be removed and cleaned. Follow the steps as detailed below under
"Specific Cleaning Steps".
Flame is deep blue in color: The burner orifice seems to
be OK. So far, so good. Continue on to the next step. Photo #3 shows the deep
blue flame touching the tip of the thermocouple and the end of the thermocouple is
Once you see a flame present, have the person on the inside
continue to hold the button on the safety valve for about 30 seconds. On a properly
adjusted burner assembly, you would normally need to hold the safety valve in
for only a few seconds. The purpose of this extra time during this troubleshooting
procedure is to ensure that the thermocouple is being brought up to full temperature.
A thermocouple that is improperly positioned may require this extra time. After
30 seconds, the person on the inside should release the safety valve button while
the person on the outside watches to see what happens to the flame.
Flame slowly goes out or goes out immediately: you probably
have a dirty or faulty thermocouple. First try cleaning the tip before buying
a new one. Follow the tasks listed below under "Specific Cleaning Steps".
Flame remains lit: appears to me that everything is running
perfectly. Enjoy your RV.
Specific Cleaning Steps:
At this point, you may have determined that you need to remove
some items, clean them, and reinstall them to check for proper action. Even if
you think that you may have a problem with only one item, I still recommend that
you remove and clean the thermocouple, the igniter, and the burner
orifice tube. Once you get one item removed, it is much easier to get to the
remaining two. So while you're in there, why not check and clean all three items.
Your task is simple: first, shut off the propane tank valve!
Step number two: double check to make sure that you have shut off the propane
tank valve! Then, remove all three items from the burner box, clean out any
and all dirt or debris that remain in the burner box area, and then re-assemble
everything. Photo #14 below shows all three items reattached to the burner box
with only the gas line fittings remaining to be installed. Once complete, follow
the Troubleshooting Steps listed above to confirm that everything works
properly. Compare the cleanliness of this photo to photo #1 above.
Gaining access to remove and re-install any of these items
with a screwdriver in this cramped area may be difficult. Stubby screwdrivers
are of little use because they generally have big, fat handles that prevent them
from being in the correct alignment with the screw to be removed. Perhaps a ratcheting
right-angle screwdriver might work best but I was able to use one of those Phillips
tipped screwdriver bits with a hex shank that is normally designed to be inserted
into the end of a screwdriver shank or other similar holding tool. Without using
any such holding tool, I merely held the screwdriver bit in place with a finger
or two of one hand, while a 1/4" open end wrench was used to turn the hex portion
of the bit with the other hand. It takes a while because you can only get about
a 1/4 turn with each movement of the wrench.
You may also find that the gas line connectors tend to get
in the way while trying to remove the screws, so you may wish to disconnect the
gas fittings in order to gain some needed work space. Note that photo #4 above
shows the gas line fittings are the last item to be re-installed. This makes for
a little more maneuvering room when trying to re-install the screw to any of the
The thermocouple probe will probably have to be removed just
to gain access to the screws that hold in the igniter and the burner orifice
so start by removing the thermocouple and it holding bracket. It is all held
in place with one small Phillips head screw. Once the screw is removed, the
entire holding bracket and thermocouple can be removed from the burner box.
Try not to disturb the position of the thermocouple relative to its holding
bracket. There is no need to remove or reroute the remainder of the copper line
of the thermocouple that leads up to the control panel because there should
be enough slack to examine and clean the tip of the thermocouple in place. Photo
#5 below shows the thermocouple and its holding bracket removed from the burner
The tip of the thermocouple will be discolored due to heat
from the flame and this is normal. However, the tip should be uniform in shape,
not distorted, and without any particles or debris clinging to the end. Use
the fine emery cloth or green scratch pad to thoroughly clean and smooth the
tip. I used one of those green "scratch pads" generally found in the sandpaper
section of a hardware store. These scratch pads are similar to, but the not
the same as the pads sold for cleaning and washing pots and pans. They have
no sponge and no embedded detergent.
Normally you should not have to re-position the thermocouple
in relation to where it sits with the flame. However, repair attempts by others
may have left the thermocouple holding bracket either distorted or bent. The
final position of the thermocouple tip is not absolutely critical but at least
1/4" of the tip must be fully immersed in the blue flame. Photo #6 below shows
the thermocouple and igniter both in the midst of the deep blue flame. A much
lighter colored blue flame extends slightly over these items but it is barely
discernable in the photo. Also note the holding bracket for the thermocouple
and how it is slightly bent to achieve the proper position.
If the bracket is bent or distorted and the tip of the thermocouple
just barely touches the flame or doesn't touch it at all, then it will not be
brought up to full temperature and therefore no signal to signify the presence
of a flame will get generated. And then once you release the safety valve button,
it will automatically stop the flow of gas because it thinks there is no flame
present. The presence of debris and burnt particles on the tip of the thermocouple
form an insulating jacket or pull heat from the tip of the thermocouple and
prevent it from being brought up to full temperature. Then the same shut down
procedure will happen once the safety valve button is released.
The igniter is held in place with one small Phillips head
screw which is probably the most difficult screw to access as it tends to be
blocked by the thermocouple which may need to be temporarily removed. There
is no need to remove or re-route the wire itself as there will be enough slack
to examine and clean the tip as needed. The tip should be L-shaped with the
shortest portion of the L being held in the flame area just over the flame area
of the burner orifice. Photo #7 below shows the igniter with it screw mounting
flange being removed from the burner box.
Once the igniter is removed from the burner box, use a fine
piece of emery cloth or granite sandpaper to clean the end that normally sticks
into the flame. This end will normally be discolored from the heat but try to
make it as clean as possible without any debris or particles being burned onto
the tip. Once the igniter tip is cleaned thoroughly, simple replace it in the
burner box and re-install the screw.
The igniter should be properly positioned with the correct
gap automatically unless the tip has been bent. Normally the gap between the
igniter tip and the burner orifice tube should be between 1/8" and 3/16".
If the flame is yellow or flickers erratically, then the
burner orifice is probably plugged and/or dirty. Removal is similar to the igniter
and thermocouple in that one screw holds it in place on the burner box bracket.
In addition, the gas line must be disconnected so that the burner orifice can
be removed for cleaning.
Always use two wrenches on all gas line fittings: one to
loosen a fitting and another to hold the mating piece stationary. Failure to
do this may cause the copper gas line to bend or create a leak at another fitting.
Photo #8 below shows the gas line disconnected and the retaining screw being
removed from the flange around the burner orifice tube.
Photo #9 below is a close up of the gas outlet
slits in the burner orifice tube once it has been removed from the burner box.
Note the debris and small particles around the slits especially the slit closest
to the mounting flange. This one is not particularly dirty but the slits still
need to be perfectly cleaned out. The actual orifice is just off the left side
of the photo and is part of a brass fitting. Just to the left of the screw mounting
flange are the three air inlet holes.
Once the burner orifice assembly has been removed from the
burner box, examine the tip where the gas outlet slits are cut into the metal.
Soot and other debris may eventually build up here blocking one or more of the
outlet slits. Use fine emery cloth or the green scratch pad to remove the debris
and thoroughly clean the tip.
Use only alcohol to clean the burner orifice; do not use
gasoline or any other type of solvent. Any residual of those chemicals may burn
off with excess soot and carbon build-up. Do not use a pin or wire to poke into
the orifice tube. You can fill up a small drinking glass with alcohol and allow
the burner orifice to soak for several hours if there is any build-up of soot
or carbon. To make sure the orifice is not plugged, try holding your fingers
over the three air inlet holes and blowing into the brass fitting while holding
the extended portion of the orifice tube in the alcohol. You should see bubbles
coming out of the gas outlet slits. If not, things are still plugged up. Photo
#10 below shows the cleaned burner orifice tube ready to re-install in the burner
Once the burner orifice is attached, then reattach the gas
line fittings using two wrenches. These are flare nuts and compression fittings
and no pipe dope or Teflon tape is needed.
There are no positional adjustments to the burner orifice
and there are no provisions for adjusting the size of the orifice or air mixture.
Once you go through the troubleshooting steps again, everything should work
just perfectly. If a yellow flame continues to appear after cleaning the burner
orifice, then the air mixture is still not correct which means something is
wrong with the mechanical set-up of the burner orifice and the only remedy is
to purchase a replacement burner orifice. (See the
Operator's and Parts Manuals above.)
If everything checks out and the propane lights on first
try and stays lit, then pat yourself on the back for doing a good job. You just
saved about $100 to $200 in charges and you have the peace of mind knowing that
you did a complete and thorough job.
If you are still have problems keeping the flame lit and
you know for sure that the burner orifice is clean along with the burner box
, then the thermocouple may need replacement. This page also includes a complete
description of replacing the thermocouple.
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Changing the Thermocouple on the N300.3 (Model HD)
Many thanks to Richard Cox for providing the following description
and photos of this procedure. The N300 is the larger refrigerator with a freezer
compartment found only the Rialta Model HD. The other models, FD and QD, have
smaller refrigerators and the procedure would be very similar. Other owners are
encourage to submit their own description and photos for those models. Also, in
reading the following, please remember that the HD uses a meter with a needle
that points to either a red or green area on the meter face. Other models use
only a green light.
Recently, the refrigerator in our 2002HD Rialta, Norcold 300.3
stopped working in the propane mode. As it had previously worked during a recent
trip on both 12 volts and 120 volts, I knew that there could not be anything wrong
with the cooling unit. The problem therefore must be somewhere in the propane
workings. I had nearly a full tank of propane. I lit a burner on the stove for
a minute or so and I tried to start the refrigerator in the gas mode. The needle
on the front panel meter moved upscale very shortly after depressing the igniter
button several times rapidly but dropped back towards the low end as soon as I
released the right hand red button. Apparently, the flame was starting but then
going out after I released the button. To confirm this, I went outside, removed
the lower vent grill and opened the cover to the combustion box. I then had my
wife go through the motions of attempting to start the refrigerator once again.
Sure enough, as soon as she punched the igniter button with the right red button
depressed, the flame started immediately in the burner box. But as I suspected,
as soon as she released the right hand button, the flame went out. Conclusion,
our refrigerator had a bad thermocouple.
A thermocouple is a device consisting of a junction of two
dissimilar metals usually that will generate low levels of electrical current
in the millivolt range when the junction is exposed to heat or cold. In RV refrigerators,
the thermocouple is used as a safety device to shut down the flow of gas should
the flame be inadvertently extinguished. The lower end of the thermocouple has
a probe housing the junction. This is positioned in the combustion box directly
above the flame which heats the coils. The low voltage signal thus created by
the flame is transferred by the thermocouple to the interrupter. This voltage
signal activates a low level magnet which will hold the interrupter and the safety
valve open. The magnet itself will not pull the safety valve open but once opened,
the magnet is strong enough to hold it in the open position. The valve is initially
opened by pressing the right hand red button on the front panel. If the flame
lights and the thermocouple sends a signal to the interrupter, the flow of gas
will continue when the right red button is released. If the flame goes out when
the red button is released, then the thermocouple is bad.
Purchase of the replacement thermocouple
Because we live in a remote rural area, I find it more convenient
and less expensive in the long run, to purchase replacement parts on-line or by
phone. I called Lichtsinn’s and they had a replacement Thermocouple – Norcold
part number 619154 or Winnebago part number 131147-01-729. The cost was $25.95
with their summer discount of 5% [winter discount is 10%]. The part arrived a
few days later via UPS to my door.
I subsequently checked a local hardware store for any thermocouples
that might fit but the only ones that they had were for domestic gas hot water
heaters. The probe length was too short, the upper connection was the wrong size
and the maximum overall length was too short. I also looked on-line. I saw one
site that was selling used Norcold thermocouples for $10. The site did not say
if they had any available for the Norcold 300.3. They listed a phone number to
call for additional information. I thought that if I was going to make the effort
to remove the refrigerator, it would be much better to purchase a new Thermocouple
rather than a used one.
Removing the refrigerator
decided that it would be easier to replace the thermocouple, if I removed the
refrigerator from the Rialta. This would provide unlimited physical access to
the parts involved in the replacement. The thermocouple, or TC for short, [a 54”
long copper tube] has its probe positioned inside the burner box at the lower
left rear of the cabinet. From there the tubing goes horizontally across the rear
of the cabinet to the right side and then up to the top of the cabinet, where
it follows across the top to the center of the cabinet to the interrupter. The
interrupter is directly behind the right red button on the control panel. The
upper end has a brass fitting which threads into a mating hole in the interrupter.
I began by turning off the gas supply at the tank making sure
that the valve was tight. I removed the lower outside vent grille to gain access
to the rear portion of the refrigerator. I unplugged the 120 volt supply cord
from the receptacle on the left. The 12 volt wires were removed from the terminal
block (yellow and white wires). I turned the gas valve that is part of the refrigerator
to the “OFF” position. I removed the two lock nuts on the bolts that fasten the
refrigerator to the hold down brackets. The bolts are positioned with the heads
down, the threads up and the nut on top. Some bending of the brackets was necessary
to remove the bolts. I disconnected the gas supply line at the junction of the
copper supply tube and the gas line that goes to the refrigerator. I used two
wrenches, one on each side of the connection to avoid damage to the fitting. I
went inside the coach and removed the refrigerator door by removing the top screw
on the hinge, noting the position of a plastic washer. I also took out the six
Phillips head screws from the side of the refrigerator case and it was ready to
be removed. I initially pushed on the back of the refrigerator case from the outside
until I moved it inward about 4 -6 inches. Working from inside the coach, I pulled
it out of the cabinet the rest of the way. It is not particularly heavy but its
bulk makes it a bit cumbersome. I tried not to grab the piping in the back for
use as a handle to avoid any possible damage to the cooling portion. With the
door off, I could position one hand partially inside the box in order to lift
the refrigerator. Once it was out if the cabinet, I carried it out the side door
of the coach. I positioned it on two saw horses which gave me easy access to all
of the parts.
Old thermocouple removal
I made mental notes on how the TC was routed before actually
taking it out. There are three nylon cable ties holding it in position along the
vertical run along the right side of the box. I snipped those loose, pulled the
probe end out of the burner box, unthreaded the brass fitting from the interrupter
and pulled the TC out of its position. I was then ready for the installation of
the replacement TC.
New thermocouple installation
I uncoiled the new Thermocouple and straightened it out to
its full length….54”. I inserted the probe end into the burner box and routed
the rest of it similarly to the old one and positioned the upper end near the
interrupter so that I could thread it into the interrupter opening. I snugged
the fitting gently but firmly. I installed three new cable ties in approximately
the same position as the old ones and the refrigerator was ready to go back into
the coach. I would like to have tested the refrigerator operation before reinstalling
it. However, I did not have any means of supplying gas to the refrigerator while
it was out of the Rialta.
Conside a complete cleaning of the heating elements
At this point, you have installed the new thermocouple and
are ready to re-install the refrigerator. However, take a good look at the back
side. As long as you have the entire thing out and sitting on the bench, why not
consider doing a complete maintenance of the burner and heating tube assemblies
and at the same time, cleaning up some of that rust so the thing will look new
If you'd like to consider this option, just continue on. On
the other hand, if you think everything is clean enough and you just want to put
the thing back together, then jump ahead to the next section entitled "Putting
the refrigerator back in the Rialta".
Take a good look at these two pictures.
This is the same identical refrigerator but only one day later,
after the black metal parts were cleaned of the surface rust and a new coat of
If you want, you can click on either picture to see a high
resolution image but be prepared for a very close up look. If your web browser
resizes the picture to all fit in the window, look for the resize gadget in the
lower left such as found in Internet Explorer v6 to resize the image to its full
what's so important about having a nice black shiny paint job on the parts of
the refrigerator that you don't even see? These parts are painted black for a
reason: heat transfer. Technically, your refrigerator makes things cool by first
heating up some of its parts. After some magic is done with the ammonia gas to
create the cooling inside the refrigerator, these black painted parts must now
shed some of that heat. Take a look towards the top of the refrigerator and notice
one tube with a bunch of cooling fins on it just like a radiator. Metal finishes
that are smooth and black will transfer away more heat energy than a metal finish
that is rusty and covered with dirt.
To accomplish this refurbishment, a lot depends on just how
detailed you want to get. To be done thoroughly, you will need to remove the insulation
around the heat pipes and chimney. There you will also see the actual 12V heat
element and the 110V heat element. Both can be removed and a little emery cloth
used to shine up the working end of the heat elements.
can begin by carefully cutting the aluminized foil wrap around the insulation.
Look at the next photo and you will see that this insulation is really two half
round pieces that are held together by nothing more than the aluminized foil.
You can see or feel exactly where the pieces join together. Use a razor blade
or sharp knife to cut right along this joint. Remove the two halves of insulation
to expose the heat pipe area.
the insulation removed, you can see where the two heating elements are attached
to the heat pipe. Now the design of the entire heating area becomes obvious. Either
the propane flame or one of the electrical heating elements are used to heat up
the gas inside the large tube. The two electrical heating elements merely sit
in a round tube of their own. All of these vertical heat tubes are welded to the
main tube that contains the ammonia gas. The idea here is simple: whatever form
of energy is used, it's only function is to apply heat to this area of the tube
with the ammonia gas. The insulation is only used to concentrate the heat in one
area and to keep ambient air from cooling off this area.
can remove the electrical heating elements and used some emery cloth to remove
surface rust. With the entire heating area now exposed, its clear that a lot of
rust forms in this area. Use a stiff wire brush wheel on an electric drill to
remove as much of the surface rust as possible. Use sandpaper or emery cloth to
get into the areas the wire wheel can't reach. Continue to clean up as much of
the black painted areas of the refrigerator as you determine to be necessary.
When you are satisfied (you won't get everything down to bare
smooth metal), you are now ready to apply a new coat of black paint.
to be neat here as you don't want black overspray all over the other areas of
the refrigerator covering wires and other gas tubing parts. Use newspaper to cover
those areas and mask off with tape. It only takes a few minutes where you can
protect everything. Here's a tip: it will take three or more light coats of a
gloss black enamel to get a good looking coat. Use a fast drying paint so that
you don't have to wait a day between coats. With a little patience, you finished
product should look something like the photo on the right. And when you first
use your thoroughly cleaned refrigerator, it'll bake the new paint as it heats
up so it sort of smells just like a new one.
Here's a tip from another Rialta owner whose fridge did not
work at all on gas and barely got cool on electric:
These old absorption units can be real troublesome if not kept
clean and mine was full of rust so I removed the burner and cleaned it. Now for
an old trick from my days as a refer repair man. Go to Wally World and purchase
a 12 gage shotgun cleaning kit. It will contain a round wire brush on a metal
pole. Attach the brush to an electric drill and polish out the heat riser tube
in the fridge. Be sure to remove the spiral heat deflector inside the tube it
hangs on a wire that is attached to the top of the tube. Polish out all the rust
in the tube also remove any rust from the heat deflector. Now put it all back
together and then turn the refrigerator upside down and let it set over night.
This causes the fluids to circulate in the system and dissolve any of the solids
that may have formed due to the refrigerator being run unleveled. It is not as
much of a problem in these small fridges but the larger ones can get “vapor locked
“if run unleveled. Turn the unit right side up and let it set for another 12 hrs
then it is ready to reinstall.
Putting the refrigerator back
in the Rialta
This was basically the reverse procedure of removing it. After
it was positioned in the cabinet, I connected the two tie down bolts in the back
first and then reinstalled the screws around the front of the cabinet. I did not
install the door until after I had checked operation of the refrigerator. After
making the electrical connections (the white wire is -12 volts while the yellow
wire is +12 volts; there are + and – markings on the terminal strip where the
12 volts connections attach), I reconnected the gas supply line. I opened the
refrigerator valve, then the tank valve and went inside for a test. As the tank
had been off for a bit, I first lit a range burner to allow the gas to refill
the supply lines. I set the mode switch to gas, held the right red button down
and then pressed the igniter button repeatedly until I saw the meter read upscale.
After I was sure that it was well upscale, I released the right red button and
the meter held its position. As a further check, I went outside, peeked in the
inspection hole in the burner box and sure enough the gas flame was burner merrily.
It was a nice blue flame and properly positioned. I repeated the startup process
several more times. Each time the refrigerator started quickly and the flame stayed
lit. I went back inside the coach and reinstalled the refrigerator door.
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317-881-3273. All types of models, and he even has some new, and rebuilt models
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