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RV Appliances

How to Tell if an RV Thermostat is Bad? – Troubleshooting Guide


by Yessenia Blanda

/ fact checked by Sam Howard

how to tell if an rv thermostat is bad

To take advantage of your awesome life on wheels, it’s important that every component of your RV is working properly – including your thermostat.

If you are not knowledgeable about this issue, you may be wondering how to tell if an RV thermostat is bad. Most often, a thermostat needs repairing when it is not regulating the temperature correctly, causing your heater to run excessively or your air conditioner to stay on too long.

Once you have located the problem that needs attention, you can use the tips below for troubleshooting and get your thermostat back to working condition.

How to Know if an RV Thermostat is Not Working?

A bad thermostat can leave you suffering from high utility bills and even other engine-related issues. Here are some common symptoms of a bad wall thermostat:

1. Your RV heater won’t turn off

If you have a gas furnace in your RV, it should shut off automatically when the temperature reaches a certain point. If it’s not doing that and keeps running, there could be a problem with the thermostat.

2. The temperature fluctuates wildly

If you have a problem with the RV thermostat, you will notice that the temperature in your camper or trailer does not remain consistent. You might also see that when you turn on the heater or air conditioner, there is no change in temperature.

3. Inaccurate temperature readings

If your thermostat’s temperature gauge reads higher than normal when driving, this could mean that your thermostat is broken or stuck closed. This increases pressure in the cooling system, causing overheating problems and possibly damaging other components in your RV’s cooling system.

4. Heater malfunctioning or won’t come on

A stuck open thermostat can lead to excessive coolant flowing into your engine. Instead of getting hot air when you need it, what you’ll get is the opposite.

RV Thermostat Troubleshooting

If you have RV thermostat problems, it’s important to know how to diagnose and fix the issue. The thermostat is an essential part of your heating and air conditioning system. If it fails, you could be left without heat or cool air when you need it most.

Here are some RV AC thermostat troubleshooting tips that can help identify the problem:

1. Check the wiring connections

The first thing you should do when troubleshooting a thermostat problem is check the connections of the wires.

Make sure they are all connected securely and in good condition. Check for signs of any loose or frayed wires. Replace them immediately with new ones before proceeding with any other repairs.

2. Check the power source

Check the batteries and fuses. Your thermostat’s issue could be a simple power issue. If the batteries are drained, the system will not work properly. Replace all batteries with new ones, and make sure that all fuses are in good condition.

How to Replace a Bad RV Thermostat?

What to prepare:

  • Gloves
  • Screwdrivers
  • Marker and masking tape for labeling

Step 1: Pick A Good RV Thermostat


Whether it’s for a Dometic thermostat, or a Coleman Mach thermostat, you will have to choose the right kind of thermostat for your RV. There are four different types:

  • Analog: These are just like regular wall-mounted thermostats. They don’t have any electronics or batteries, and make use of a heat-sensitive metal to provide temperature control.
  • Digital: This type of RV thermostat uses a digital display instead of an analog one. It makes use of electronic temperature sensors which are usually powered by wires.
  • Smart: These RV thermostats cantake both your pre-determined setting as well as adjust accordingly to the environment.
  • Programmable: This type of RV thermostat allows you to set precise temperatures during different times of day so that your heating and cooling systems work more efficiently than they would otherwise.

Make sure that your replacement RV thermostat comes with a high rating and is compatible with your RV. Thermostats come with ratings based on their ability to control the temperature.

It’s important to select one that has a high rating, especially if you live in an area where temperatures fluctuate often during the year.

Step 2: Make sure there is no power to RV thermostat

Shutting off the power supply to the thermostat is very important in order to prevent electrical shock. You can do this by turning off the circuit breaker on the power source and then disconnecting the wires from your unit. Check your RV’s owner’s manual, such as a Dometic RV thermostat manual, for specific instructions that you are otherwise unsure of.

Step 3: Remove the old thermostat

Remove all of the screws from around your old thermostat and then remove it from its housing.

Make sure that you don’t lose any of these screws as they are used for mounting purposes.

If you can’t remember where they came from, use masking tape to mark each one with its location before removing them from your unit. This will make it easier when installing new ones later on.

If you’re replacing an old thermostat, you may have to remove some wires connected to it first before removing the mounting plate.

Inspect the wires coming out of the wall and going into the thermostat. Make sure they are properly labeled before removing them so you know which wire is which.

Step 4: Mount and Install The New Thermostat

  • Make sure that your mounting bracket is securely in place. You might have to drill a hole into the wall and insert a screw through the housing for mounting if the positioning is a little bit off.
  • Reconnect those same wires to their corresponding terminals on your new thermostat.
  • Determine which wire goes where based on your photo or notes from when you removed the old unit.

Step 5: Run a quick test


Test out the camper thermostat by turning on the power supply and setting it to different temperatures in order to make sure that it works properly before installing it permanently.


How do I test my RV thermostat power?

You will need to use the multimeter as a voltmeter. This is the easiest method since you don’t have to cut off the power source or disconnect any wires.

A good sign is a reading between 22-26 volts. If there is zero voltage coming into the thermostat, then it’s bad and needs to be replaced.

Can I replace my RV thermostat with any thermostat?

You can certainly buy a standard home thermostat for your RV but we strongly recommend that you use a thermostat specifically designed for RVs because of the difference in the electrical system.

RV thermostats run on a 12-volt system while residential and commercial thermostats typically use a 24-volt system.

How do I reset my thermostat in my RV?

This method can be used on virtually any type or model of thermostat. Locate the manual reset button on your unit and push it in with your finger or pen for about 10 seconds.

A unique case is for a Dometic 3 button thermostat where you have to press and hold the zone and mode buttons at the same time after turning off the power.

If your thermostat has no switches or buttons on it, unplug it from its power source and wait for about 1 minute before plugging it back in again. You can cut off power either by switching off the breaker or removing the fuse.


A good thermostat will help you stabilize your temperature, keep you comfortable and save money on energy costs, so it’s worth looking into ways to test and replace yours if it’s malfunctioning. If something is wrong with your thermostat, it’s important to address the issue promptly to avoid extensive damage.

Hopefully this article gives you a starting point in troubleshooting your RV’s thermostat, whether it is bad or has stopped working altogether. Use the information provided here to help you understand how to tell if an RV thermostat is bad.

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Yessenia Blanda

Hi, I’m Yessenia. I love traveling and being on the road, and I want to share my experience with people who are looking to have some adventures of their own. 

Whether you’re a new or experienced RVer, I hope you’ll find something here that helps you on your journey.