10 Common Dometic RV Thermostat Problems Solved!

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Hey there, fellow RV enthusiasts! Having heat and air conditioning is one of the best perks of camping in an RV. When your thermostat isn’t working as it should, it can make life in your RV pretty uncomfortable.

My husband (a certified RV technician) and I have seen our fair share of thermostat woes on the road. If your Dometic RV thermostat isn’t working, we have the solution. So, let’s skip the fluff and get right to the heart of the matter—common Dometic RV thermostat problems and the solutions you need.

Common Dometic RV Thermostat Problems

The Thermostat Display is Blank

Problem: You turn on your thermostat, but the display remains stubbornly blank and no lights turn on.

Solutions:

• Check if the thermostat is receiving power. Make sure your RV is plugged into a power source and that the house batteries are in good condition.
• Inspect the thermostat’s wiring for loose or disconnected connections. Reconnect any wires that may have come loose.
• Check the fuse for the thermostat to make sure it is not blown.
• If everything seems fine but the display is still blank, consider replacing the thermostat.

The Thermostat Won’t Turn On

Problem: The thermostat’s display is working, but it won’t respond when you try to adjust the temperature.

Solutions:

• Try the to turn on both the heat and the cool settings. If one works and other other doesn’t then the issue is probably with the furnace or air conditioner and not the thermostat.
• Adjust the temperature setting further. If it’s set too close to the current temperature inside the RV, the thermostat may not kick in.
• Try resetting the thermostat. For a single zone Dometic RV thermostat, simply press the “+” button and the “On/Off Mode” button at the same time until you see two dashes. Then turn the thermostat on and back off. See your owner’s manual for factory reset instructions for other Dometic thermostat models.

Temperature Fluctuations

Problem: The thermostat can’t seem to maintain a consistent temperature in your RV.

Solutions:

• Ensure that your RV is adequately insulated. Poor insulation can lead to temperature fluctuations.
• Check for drafts or air leaks around windows and doors and seal them if necessary.
• Clean or replace the air filters in your RV’s AC units regularly. A clogged filter can affect temperature control. Click here for full AC maintenance instructions.
• If the problem persists, it might be an issue with the thermostat’s sensor. Contact a professional RV technician for further inspection and potential replacement.

The Fan Runs Continuously

Problem: Even when the thermostat reaches the desired temperature, the fan continues to run.

Solutions:

• Check the fan mode setting on your thermostat. Make sure it’s set to “Auto” or “Au” rather than “On.”
• If the issue persists, there may be a problem with the fan relay or the thermostat itself. Consult an RV technician for a diagnosis and potential thermostat replacement.

Inaccurate Temperature Reading

Problem: The thermostat displays an inaccurate temperature reading or turns off the heating or cooling before the desired temperature is reached, making it difficult to set the desired comfort level.

Solutions:

• Use an external thermometer to verify the actual temperature inside your RV. If it doesn’t match the thermostat’s reading, it is not properly calibrated.
• Unfortunately, RV Dometic thermostats do not have a calibration feature. Try the factory reset of the thermostat as detailed above.
• If the problem persists and you are not able to properly cool or heat the RV, it might be time for new thermostat.

Thermostat Keeps Clicking On and Off

Problem: The thermostat seems to be constantly cycling your HVAC system on and off, leading to discomfort and potentially excessive wear on your equipment.

Solutions:

• Check if the temperature differential setting is too narrow. Adjust it a few degrees higher or lower, which should prevent the thermostat from cycling too frequently.
• Ensure the thermostat is not placed near heat sources, direct sunlight, or drafts, as this can cause temperature fluctuations.
• If the problem continues, it could be due to a faulty thermostat or a wiring issue. Consult an RV technician for further investigation.

The Display is Showing Celsius Temperatures

Problem: The thermostat is showing temperatures in Celsius, but you want it to show degrees in Fahrenheit (or vis versa).

Solutions:

• This one is a simple fix. For a single zone Dometic RV thermostat, simply press the “+” button and the “-” button at the same time until the tempature scale changes.
• See your owner’s manual for temperature scale reset instructions for other Dometic thermostat models.

Unresponsive Buttons

Problem: The buttons on your Dometic RV thermostat don’t respond when you press them. This applies to newer Dometic thermostats, such as the one shown above.

Solutions:

• Gently clean the buttons with a soft, dry cloth to remove any dirt or debris that might be obstructing their function.
• Try gently tapping the buttons (as you would a touch screen device) instead of pressing the buttons. Newer Dometic LED RV thermostats were built to be used this way.
• If cleaning doesn’t work, inspect the thermostat for signs of physical damage. If you find any, it may be time for a replacement.

E1 Error Code

Problem: Your thermostat shows an E1 error code, which indicates a loss of communication between the thermostat and power module boards.

Solutions:

• First try a factory reset of your thermostat to see if the error clears.
• Check that the RV power’s sources are all functioning properly and inspect the fuse.
• If the temperatures are extremely high outside, this error code will also be shown. Try to find an alternative way to cool your RV down or wait for temperatures to drop. Some RV owners have reported success blowing a can of compressed air into the thermostat to lower the temperature.
• If the thermostat is still not working, there is likely an issue with the thermostat, the control panel or the connections between them. Contact an RV technician for further investigation.

E7 Error Code

Problem: Your thermostat shows an E7 error code, which indicates a loss of 120 Vac power to all power module boards on the system.

Solutions:

• Make sure your RV is connected to shore power and check the breakers on the power pedestal. Also check that your RV power cord is not damaged.
• Check the fuses for your thermotstat and air conditioners.
• If your RV has multiple AC units, check if both units are working. If only one unit is malfunctioning, it may have been damaged in a power outage and need a professional repair.
• If your RV has an onboard generator, turn off the shore power and try running the air conditioner using the generator. If the unit runs using power from the generator, your transfer switch is the problem. The transfer switch will need to be cleaned or replaced.

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In conclusion, a malfunctioning Dometic RV thermostat can put a damper on your RV adventures, but armed with these common solutions, you’ll be better equipped to tackle thermostat issues head-on. Remember, when in doubt, consult with a qualified RV technician who can diagnose and resolve more complex thermostat problems.

Happy Camping!