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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
