Norcold N300.3 User manual

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Norcold N300.3 Refrigerator
This article is taken from the Winnebago Rialta Owners web site with the permission of the site owner. It
has been modified to remove motorhome-oriented terminology, and insert TrailManor-oriented
terminology. The scattered parts have been re-united and organized. And the Table of Contents has been
added.
DISCLAIMER AND WARNING This article deals with disassembly, repair, and reassembly of a
propane burning appliance. Propane is dangerous, and nothing in this article mitigates that danger.
It is recommended that unless you are well-trained in propane burning appliances, you engage a
certified repair technician to perform the work described herein.
The original article is located at http://www.rialtainfo.com/winnebago/refrigerator.htm
Table of Contents
Section Title
Page
Part 1 - General Information
2
Operators’ Manuals
2
Refrigerator FAQs
3
Levelling the Refrigerator
4
The Stated Requirement
4
The Real World
4
Levelling Measured at the Wheels
5
Conclusions
5
Levelling Measured at the Countertop
5
Summary
6
Maintenance and Cleaning
6
Part 2 - Troubleshooting and Repair
7
Troubleshooting Electrical Operation
7
Troubleshooting Propane Operation
7
Introduction to Troubleshooting the Burner
8
Troubleshooting Steps - Propane Burner
8
Results of Troubleshooting
9
Cleaning
10
Cleaning the Tip of the Thermocouple
11
Cleaning the Igniter
13
Cleaning the Burner Orifice Assembly
14
Part 3 - Replacing the Thermocouple
16
Background
17
Purchase of the Replacement Thermocouple
17
Removing the Refrigerator from the Trailer
17
Old Thermocouple Removal
18
New Thermocouple Installation
20
Cleaning And Repainting The Rest Of The Mechanism
21
Another Cleaning Idea
24
Putting the Refrigerator Back in the Trailer
25

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Part 1 - General Information:
TM installs a Norcold model N300.3 refrigerator in every trailer model. The “.3” suffix on the
model number indicates that it is capable of running on three different power sources: propane
(LPG), 12 VDC, or 110 VAC.
This is 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 purpose while
traveling.
1. The AC Mode of operation should be chosen when you have a shore power connection either
at home or at campsites that can provide 110 VAC power.
2. 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.
3. 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 is a modification available which will allow for thermostatic control in
this mode.
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.
Operator's Manuals for Norcold Model N300:
Installation & Owner's Manual (990k)
Parts List (632k)
Service Manual (830k)
Service Bulletin - Checking for problems in LP mode (101k)

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Refrigerator FAQs:
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 produces a spark when you push the button on the front control panel.
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 "Levelling the Refrigerator below."
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 and Cleaning."
► 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 center.
► Make sure the gas supply is LP gas only and not butane or a butane mixture.

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► 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 or decreased.
► 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.
Does it require 12VDC to operate when using LP gas?
No. The refrigerator will operate standalone on LP gas.
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.
Leveling the Refrigerator:
There is an old myth that absorption refrigerators must be almost perfectly level, or they won’t
operate and may be harmed. Is this myth still true?
The Stated Requirement:
The manual for the Norcold refrigerator says that its "operational limits are 3 degrees off-level
side-to-side and 6 degrees off-level front-to-back, as looking at the front of the refrigerator".
What does this mean? Remember that the refrigerator is installed sideways in the trailer, so side-
to-side for the refrig means front-to-back for the trailer. Similarly, front-to-back for the refrig
means side-to-side for the trailer.
The Real World:
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:
1. At the wheels, since this is where you level the trailer itself.
2. At the flat counter-top immediately above the refrigerator using a small 24" long bubble-spirit
level.
Levelling Measured at the Wheels:

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Let's first take a look at the wheels and visualize the variation from level that would still allow
the refrigerator to operate properly.
Conclusions:
1. The TrailManor trailer can out of level side-to-side (wheel-to-wheel) by as much as 9.5 inches
without exceeding the refrigerator spec of 6 degrees. In other words, one wheel can be 9.5 inches
higher than the other.
2. The TrailManor trailer can be out of level front-to-back (wheels to tongue jack) by as much as
7.5 inches without exceeding the refrigerator spec of 3 degrees. In other words, the tongue can be
above or below the wheels by as much as 7.5 inches.
Levelling Measured on the Countertop:
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:
1. Lift one end of the level until the bubble is centered.
2. Measure how far you had to raise that one end of the level.
3. Compare that measurement to these sketches.

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It is apparent that the refrigerator is supposed to work properly even when it is 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, Norcold states the answer
simply as "Normal vehicle leveling to provide comfort for the occupants is satisfactory for
refrigerator operation".
Summary:
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.
Some owners use jacks 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, then it is unlikely to bother the refrigerator.
Maintenance and 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 in this document 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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Part 2 - Troubleshooting and Repair
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.
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.
Troubleshooting 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.
Troubleshooting Propane Gas Operation:
This is the mode of operation that causes almost all of the problems associated with 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 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.
Photo #1

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If you are experiencing problems running on propane, you are most likely experiencing one of
two very different problems.
Bad wire connectors at the control knob:
This is a well-known problem, and Norcold has a “service fix” for it. A number of wires are
connected to the back of the control switch (the one that selects AC - DC - GAS - OFF). Each
wire terminates with a push-on connector, which is simply pushed onto a flat blade on the switch
body. After a period of time, these push-on connectors lose their tension, and make a poor
contact with the blade half of the connection. The usual result is that the propane flame will light,
but will not stay lit. If you write to Norcold, they will send you two wires with new connectors
on the ends. A simpler answer is to pull each connector off the blade, squeeze it closed with a
pair of pliers, and replace it on the blade. Either solution requires that you pull the refrigerator a
few inches out from under the countertop, in order to gain access to the wires.
This article does not present details of this fix, but because it is simple to do, it is probably the
first action to take if you experience a propane flame that won’t stay lit.
Dirt, grit, rust, scale accumulated in the burner area:
Over time and use, many kinds of grime can accumulate in the burner area. If they build up to a
sufficient level, they can interfere with the propane burner operation, resulting in a flame that
won’t light, a flame that is weak, or a flame that won’t stay lit. The solution for all of these is a
good cleaning of the burner area. Many people have reported that simply cleaning out
accumulated dirt, soot, spider webs, etc, using a long-handled brush and a vacuum cleaner, was
all that was necessary to remedy their problems.
However, since many of the problems are related to a clogged or dirty burner orifice, or a dirty,
contaminated, or failed thermocouple, cleaning may involve removal and cleaning of the burner
parts, replacement of anything that has failed, and proper re-assembly of the burner. These items
can not be cleaned without removing them from the burner box area.
Introduction To Troubleshooting The Burner
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.
Troubleshooting Steps - Propane Burner:
1. 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.

9
Photo #2
2. Open the valve on the propane tank.
3. Turn the thermostat to its coldest or highest setting.
4. Turn the selector switch on the control panel to the gas position
5. Push and hold the safety valve button in the fully depressed position. (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.)
6. In rapid succession, push the igniter button several times for about 5 seconds.
7. 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 orifice tube.
Results of Troubleshooting :
After performing these steps, you may find one of three results.
A. 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 the burner orifice can be fully clogged and needs to be cleaned.
B. Flame present but it is yellow instead of blue or flickers erratically. You probably have a
clogged burner orifice tube which needs to be removed and cleaned.
C. Flame is deep blue in color: This indicates that the burner orifice is OK. So far, so good.
Photo #3 shows the deep blue flame touching the tip of the thermocouple and the end of the
igniter is glowing red.

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Photo #3
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. If the flame goes out slowly or goes out
immediately, you probably have a dirty or faulty thermocouple. Try cleaning the tip before
buying a new one.
Cleaning tne Burner Area and Components:
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 both propane tank valves! Step number two: double check to
make sure that you have shut off the propane tank valves! Then, remove all three items from the
burner box, and clean out any and all dirt or debris that remain in the burner box area. Then clean
each of the items you have removed. Finally, 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, repeat the Troubleshooting Steps listed above to confirm that everything works
properly. Compare the cleanliness of this photo to photo #1 above.

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Photo #4
Gaining access in order 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, 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
hardware items.
Cleaning the Tip of the Thermocouple:
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 box.

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Photo #5
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.

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Photo #6
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 be 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.
Cleaning the Igniter:
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.

14
Photo #7
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".
Cleaning the Burner Orifice Assembly:
The orifice assembly has two major parts - the orifice itself, which is a round brass plug with a
small hole drilled down the center of it, and a sheet metal tube containing air holes and a series
slits where the gas burns. Both of these may need cleaning. 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. Just to
the left of the screw mounting flange are the three air inlet holes. The brass orifice is just off the
left side of the photo and is part of a brass fitting.
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.

15
Photo #8
Photo #9
Once the burner orifice assembly has been removed from the burner box, examine the gas outlet
slits that are cut into the metal. Soot and other debris may eventually build up here blocking one
or more of the slits. In Photo 9, 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. Use fine emery cloth, the green scratch pad, or a stiff fiber brush to
remove the debris and thoroughly clean the tip. Shake out any debris that remains in the tube.
Use only alcohol to clean the brass 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

16
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 box.
Photo #10
Once the burner orifice assembly 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.
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.
Part 3 - Replacing the Thermocouple
If all burner parts have been cleaned and properly re-assembled, and the burner lights but still
will not stay lit, then it is likely that you have a bad thermocouple. This unit cannot be repaired,
and must be replaced.

17
Background
Recently, our refrigerator 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, 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 proper 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 to purchase
replacement parts on-line or by phone. I called Lichtsinn’s and they had a replacement
Thermocouple –Norcold part number 619154 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.
Removing The Refrigerator From The Trailer
I decided that it would be easier to replace the thermocouple if I removed the refrigerator from
the trailer. 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

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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 trailer, 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 of the
trailer. 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

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the interrupter and pulled the TC out of its position. I was then ready for the installation of the
replacement TC.

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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.