Refrigerator 3D wiring model
Dometic RM1350, gas side
On gas, the fridge board reads the box temperature, then sparks the igniter and opens the gas solenoid. A thermocouple tells it whether there's a flame.
Parts in this model
- 12 v feed: The DC feed to the fridge. Check it at the main terminal block.
- On/off: The panel's on/off. With the fridge on and running on gas, the board takes over from here.
- Gas solenoid: Power off, connectors off: about 49 Ω ± 10%, and open to chassis ground.
- Igniter
- Thermistor: Tells the board the box temperature. Unplug it at P2 and test from the wire side. In ice water for 8 to 10 minutes it should read about 8,000 to 10,000 Ω.
- Thermocouple: Reads above 13 mV with a flame. If it falls below 13 mV the board sees loss of flame and the igniter starts sparking.
The sequence
- Idle. The fridge is off or satisfied. Nothing on the gas side is powered.
- Turned on, reading temperature. 12 V reaches the board, and the board reads the box temperature from the thermistor.
- Gas: igniter sparks. The board sends voltage to the solenoid and the igniter on the same wire. With no flame, the resistance between the electrode and the burner is high, so the igniter keeps sparking.
- Flame lit. The flame drops the resistance between the electrode and the burner, so the igniter stops sparking. The thermocouple voltage climbs above 13 mV.
- Flame blows out. If the flame goes out, the igniter starts sparking right away. When the board sees the thermocouple fall below 13 mV, a 45 second trial for ignition starts.
Faults you can find with the meter
- Thermistor open
- Low DC volts (7.5 V)
- Solenoid coil open
- Igniter won't spark
- Thermocouple not proving the flame
- On/off switch open
Numbers
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Keep going on refrigerators
Learn it
- Absorption fridges (gas/electric)
- 12V compressor and residential fridges
- Absorption fridge won't run on gas
- Absorption fridge won't run on electric
- Is it the cooling unit?
Prove it
- Fridge won't run on gas
- Fridge is warm after unplugging
- Fridge works on gas, not electric
- Fridge won't cool on anything
- Freezer's fine, fridge is warm