Before working with the propane system, visit the Gas Safety page.
Propane heat is the third option in the AES sequence. If 120 volt is not available and the conditions for 12 volt operation are not met, the circuit board will light the propane burner when cooling is called for. Unlike manual refrigerators, which go to low flame when the desired temperature has been reached on propane, the AES propane flame is shut down when the temperature is reached.
When in gas mode and the thermostat calls for cooling, the circuit board sends 12 volt to the igniter, which begins sparking the burner electrode and also returns a signal from its "L" terminal to the circuit board, indicating that there is a spark at the burner. The circuit board then sends 12 volt to the "open" connection of the thermoelectric solenoid valve, which opens and allows gas to flow through the orifice to the burner. This condition can last for up to three minutes if the burner doesn't light. If the burner doesn't light after the first three minutes the circuit board will quit trying to light, and the red light emitting diode on the RM1303 vintage models will flash, or the "check" light on later models will come on. The refrigerator will not try to light again on propane until the refrigerator is reset by turning it off and back on again. If 120 volt, for example, were to become available during this "lock-out" mode, the refrigerator would operate on the 120 volt but the red diode or check light would still remain on, until the refrigerator is reset. The only thing the red diode or the check light indicate is that the refrigerator attempted to light on propane and didn't. They don't indicate any other problems.
Once the burner is lit, the igniter quits sparking the electrode and the "L" terminal quits sending a signal to the circuit board. After 10 to 20 seconds of no signal from the "L" terminal of the igniter, the circuit board discontinues 12 volt to the "open" connection of the thermoelectric solenoid valve. By this time, the thermocouple should be generating enough millivolts to hold the thermoelectric solenoid valve open. This allows the refrigerator to run safely on propane even if 12 volt were suddenly not available to the refrigerator. If the propane flame were to go out unintentionally, the igniter would sense this, begin sparking again, and the complete cycle would start over.
When the desired temperature is reached (determined by the thermostat), the circuit board sends a signal to the "close" terminal of the thermoelectric solenoid valve and shorts out the millivolts created by the thermocouple. This causes the valve to snap shut and the burner to go out.Troubleshooting Gas Operation
There are essentially two types of gas problems:
(1) the burner lights, but the refrigerator won't cool, and
(2) the burner won't light.
If the burner is lit and there is no cooling, be sure the refrigerator cools on 120 volt. This will divide the problem between a cooling unit problem and a gas problem. If it's determined that the problem is truly a gas problem, check out the burner, gas pressure, and baffle pages. If the refrigerator does not light on gas (when it is determined that it should), you should first know that the refrigerator functions properly on 120 volt. This indicate that the thermostat, switches, and voltage are good.
If you don't hear the "clunk" of the thermoelectric solenoid valve opening, test for 12 volt power to the "open" connection of the thermoelectric solenoid valve. Be careful. Shorting something out here could damage the circuit board. If there is voltage present at the valve and it doesn't open, then the thermoelectric solenoid valve is bad. If there is no voltage, then the problem is in the connections, the circuit board, or the igniter. After eliminating the possibility of bad connections, the more likely culprit is the circuit board. However, the circuit board is dependent on a signal from the "L" terminal of the igniter before it will open the thermoelectric solenoid valve. This is not a signal you can measure, so you'll have to guess or get the circuit board tested. Though less likely to be the problem, the igniter is considerably less expensive than the circuit board.
RV Mobile Inc. 11715 HWY 99, Everett, WA 98204
The owner of RV Mobile Inc. apparently suffered a heart attack and the original website was shut down.
It has been reposted here to preserve this wealth of information RV refridgerator information.