Dometic RV Fridge Won't Ignite Gas Mode: Quick Fix Guide

Quick Take

Your Dometic fridge has a control board issue that's preventing the ignitor from functioning when you manually switch from AUTO to GAS mode. The fact that it works perfectly in AUTO mode but fails when manually switched to GAS indicates the control board isn't sending the proper ignition sequence when you override the automatic switching. The gas valve clicking on and off followed by the CHECK light lockout is the system's safety response when ignition fails. This is typically caused by a faulty control board, corrupted memory in the board, or less commonly, a failing ignitor that works intermittently under automatic conditions but fails under manual operation.

Common Causes

The most likely culprit is the control board (see manufacturer specifications for your specific model's part number, around $180-220). When you manually switch from AUTO to GAS, the board should initiate the same ignition sequence it uses automatically, but a failing board may not properly execute this manual command while still functioning correctly in automatic mode.

The ignitor itself could be marginal - working when the board initiates ignition automatically but failing when triggered manually due to slight timing or voltage differences. Dometic ignitors typically last 3-5 years depending on usage and environmental conditions, and cost $45-65 to replace. Check if your ignitor glows orange-red when manually switching - if there's no glow, it's likely failed.

Control board memory corruption is another possibility. The board stores different operational parameters, and the manual override function may be accessing corrupted data while the automatic function uses different, intact memory locations. A full power reset can sometimes resolve this issue.

Wiring connections between the control board and ignitor can also cause this selective failure. Corrosion or loose connections may work fine under the gentle automatic switching but fail under the more abrupt manual switching operation.

Preparation

Turn off propane at the tank and allow the system to cool completely before starting any work. Remove the lower exterior access panel to reach the burner assembly and control components. You'll need basic hand tools, a multimeter, and possibly a flashlight or headlamp for visibility.

Take photos of all wire connections before disconnecting anything - Dometic fridges have multiple similar-looking connectors that are easy to mix up. Have your model number ready (usually found inside the fridge or on the exterior access panel) as control boards and igniters vary between models.

Ensure you have adequate ventilation when working around the burner area, and keep a fire extinguisher nearby as a precaution. If you smell gas at any point, stop work immediately and check all connections.

Repair Steps

Start with a complete power reset by disconnecting 12V power to the fridge for 30 minutes, then reconnecting. This clears the control board memory and resets any safety lockouts. Before retesting, ensure the system has completed its full reset cycle and any error indicators have cleared.

Test the ignitor electrical continuity first by disconnecting the ignitor leads and testing with a multimeter - you should read resistance within manufacturer specifications (typically a much narrower range). If continuity is good, ensure proper ventilation and check for any gas odors before turning propane back on. Then manually switch to GAS mode while observing the ignitor through the burner access. The ignitor should glow bright orange within 10-15 seconds (timing may vary by model).

If the ignitor glows but still won't light, check the gas valve operation more closely. With the system in manual GAS mode, you should hear the valve open and stay open for the manufacturer-specified safety timing duration during the ignition attempt. If it's cycling on/off rapidly, the control board isn't maintaining the proper ignition sequence.

Inspect all wire connections between the control board and ignitor, cleaning any corrosion with contact cleaner. Pay special attention to the ignitor leads and the gas valve connections, as these carry the manual override signals from the board.

If these steps don't resolve the issue, the control board likely needs replacement. This involves disconnecting multiple wire harnesses, so refer to your photos when reconnecting. The new board may require a brief initialization period before functioning normally.

When to Get Help

Call a certified RV technician if you're uncomfortable working around gas appliances or if you smell gas during your diagnosis. Gas leaks require immediate professional attention and should never be ignored.

If replacing the control board doesn't resolve the issue, there may be a deeper electrical problem requiring diagnostic equipment most DIYers don't have. Professional diagnosis typically costs $100-150 but can save money compared to replacing multiple parts unnecessarily.

Consider professional help if your Dometic fridge is still under warranty, as DIY repairs may void coverage. Extended warranties often cover control board failures, potentially saving you the $180-220 replacement cost.

If you discover multiple electrical components failing simultaneously, this suggests a power supply issue that requires professional diagnosis. Problems with the 12V DC distribution panel, converter-charger, or wiring harness can damage multiple fridge components and need systematic troubleshooting beyond typical DIY scope.