Fridge: dometic lower board + rm7030/7732 diagnostics

Which board

Dometic 2- and 3-way absorption fridges use a lower (power) board in the back at the lower vent, and an upper board/eyebrow display inside. They talk over the 5/6-wire harness plugged into P1 on the lower board. Lower boards come as the 'Universal' board (uses a separate relay for the DC heater) and the 'Integrated Ignition' board (built-in re-igniter, 3-try ignition).

Lower board connections

P1|5/6-wire harness to the eyebrow (communication)

P2|Thermistor (2-pin)

P3|Gas valve / relay (ground)

FUSES|5 A 120V (AC) and 3 A 12V (DC) on the board

DC IN|12VDC + from battery (J1 Universal / J4 Integrated), negative/frame ground

AC|J5 AC line in, J6/J7 neutral, J8 output to the heater

Test the 5/6-wire harness

Unplugged from P1: check continuity of each wire and that none are shorted to chassis ground.

Plugged into P1, fridge ON: red (-) to orange (+) = power up to the eyebrow. No voltage = 3 A fuse and power at the terminal block.

Red (-) to green (+) = gas mode signal down. Red (-) to black (+) = electric mode signal down.

RM7030 / RM7732 built-in diagnostics

With the power switch OFF, hold the temperature selector DOWN. Keeping it down, turn the main ON/OFF switch ON and hold for 3 seconds. Each mode and temperature lamp lights twice in sequence, the CHECK lamp flashes, and the #1 temperature lamp stays on. Press AUTO/GAS down for the automatic test: each load is energized about 4 seconds. Every lamp lighting = display board is good. It exits after about 4 minutes or when power is turned off.

RM7030 / RM7732 board checks

DC first: yellow (+) to green (-) on the 6-pin connector should equal the terminal block. If not, fuse and wiring.

Gas: more than 10.5 V from the yellow 6-pin terminal to the ground strip. Less = fix the wiring/power source first.

Gas valve: gray (+) to black (-) at the solenoid wires. 9.5 V or more = board is good, look elsewhere.

AC: below 100 VAC the board selects another mode. Above 100 V with no voltage at the heating element connection = fuses (5 A AC / 3 A DC), then board.

Upper board power: brown (10-pin, +) to blue (7-pin, -). Voltage = lower board good.

Flame sense (thermocouple type): 25 to 35 millivolts with the flame burning.

These checks must be done in sequence and at the stated terminals or the board can be damaged. A lower board burned by AC over 180 V is not a warranty board failure.

Before installing a new lower board, find what killed it. Most often it is the heating element or its wiring.

DOMETIC|Dometic Control Board Diag (lower board layouts, 5/6-wire harness test) (via myrvworks.com, OCR)

DOMETIC|Dometic RM7030/RM7732 Diagnostic Service Manual (via myrvworks.com, OCR)