Is your RV thermostat working? Here’s how to check


Is it hot in here, or is it just me? Something is not right. The thermostat is set to a cool 72, yet it feels like it’s pushing 90 in the RV. Maybe the screen doesn’t have any reading displayed at all? Sound familiar? If you are not convinced your system is running efficiently we should check the thermostat because it is possible it has gone bad.

thermostate ?
Photo ID 11106993 | © Vclements | Dreamstime.com

So, is your RV thermostat working? When your RV’s thermostat is not responding to adjustments or has a blank screen you may have a bad unit. Running tests with a multimeter, responding to error codes, or simply changing your thermostat’s batteries could get your system running again. Replacing your thermostat is fairly simple to do.

Testing your thermostat is a breeze if you follow along with the steps below that have helped many people successfully deal with the same issue as you! Don’t worry if your thermostat fails your tests, replacing it really is easy!

How to tell if your RV thermostat is bad

There are a few signs that you can look for to tell if your RV thermostat is no longer working. This like an incorrect temperature reading, blank display, and non-responsive air condition are sure-fire signs that your thermostat has bit the dust.

Temperature Does Not Match Thermostat Setting

The first sign that you might notice is that your thermostat setting isn’t matching up with the temperature of the motorhome. When you know that you have set the thermostat to cool at 72, but your family is sweating and complaining about the heat, this could be a warning that your thermostat isn’t relaying the signal properly.

Start by checking if the temperature reading on the thermostat matches the room’s temperature. You’ll need a separate thermometer to check the room temperature, an app on your smartphone will be accurate enough for this purpose.

If the readings are different then this will cause an issue. For example, if the internal thermostat thermometer thinks the temperature is 72 then, of course, the air conditioning won’t kick in since it thinks it already nice and cool.

No Display on the Thermostat Panel

Another sign your thermostat is on the fritz is the screen is blank. If your motorhome or trailer is equipped with a digital thermostat and the screen is showing you nothing then it’s no wonder your motorhome has been the same temperature for days now!

Older RVs that have analogy thermostats don’t have a display so the temperature check above is a better indicator of a bad thermostat.

AC or Heat is Non-responsive

If your air conditioner or heat will not turn on or not turn off its a good sign your thermostat has given up the ghost. On a digital thermostat decrease the temperature by at least 10 degrees past what the current air temperature is. Of course, if you are trying to check your heat increase the temperature by at least 10 degrees. For an analog thermostat move the slider well past the current temperature in the direction you want the temperature to go.

If you don’t hear an audible “click” then it’s likely your thermostat is the problem. That “click” is a relay closing sending a signal to your heater or air conditioner its time to turn on. You should also hear a “click” when your room has come to the correct temperature +/- a degree or two Fahrenheit.

If you do hear that “click” it’s possible your thermostat may not be the problem. You can continue troubleshooting your thermostat to confirm it is not the issue and you can check my other articles to help discover the issue.

Can You Fix Your Thermostat?

Fortunately, you can troubleshoot and fix or replace your thermostat yourself. You just need to be a little bit comfortable working with electricity and follow proper safety practices when dealing with power.

To start we want to gather the tools we need:

  • Gloves
  • Multimeter
  • Screwdrivers
  • Wire cutters
  • Wire strippers

Most of our troubleshooting will need the cover of the thermostat removed. This should just pop off to expose the wires, battery (if applicable), and screws.

Check the Batteries and Fuses

Your thermostats issue could be a simple power issue. Some have batteries that power the unit and it won’t work if the batteries die. This is obviously best case scenario and the quickest fix imaginable. If replacing a couple of dead batteries gets the system going again, great! If not, let’s move on.

Without a battery, your thermostat will be powered by the RV’s electrical system. All RV thermostats run on 12V so your heater will work if you aren’t plugged in.

For a 12V powered thermostat, you’ll need to check your fuses. Our RV has two locations for our fuses one in the cabin, but these are mostly automotive fuses, and one in the back. Using your owners’ manual to locate the fuse for your thermostat, it might be labeled furnace. Pull the fuse and look to see if it’s broken.

If the fuse is broken or damaged you’ll need to replace it. Make sure you use the correct size of fuse, if you grab one with a higher number (number of amps) then it’ll allow too much current through the wires which puts you at risk of an electrical fire. If you use a fuse with a lower number then the fuse will frequently blow.

Automotive Fuse
Photo ID 33547185 © Eevlva | Dreamstime.com

After replacing the fuse, check the display screen of your thermostat to see if it’s functioning again. There may be an error code present now that can help you troubleshoot. Error codes may be flashing on your display screen, and once addressed may solve your problem.

Are you able to manually reset your thermostat? Not every system is capable of a manual reset, nor will every reset require the same steps. Read through your operating manual to see what the proper steps you need to take in how to reset your system.

How to Test the RV Thermostat Wiring

Moving on to testing the wiring which leads to the back of the thermostat. Here is where it gets a bit more technical, and it is perfectly ok if you are not comfortable with this step. Read through this section thoroughly before continuing, or deciding to call on professional help. You will need the assistance of someone to turn the thermostat on while testing.

For these steps you will need your a multimeter. A multimeter will read voltage, resistance and current, and can be used to see if your thermostat is getting the proper power.

This step is only applicable if your thermostat is not battery operated. If it’s battery operated and changing the batteries did not fix the issue then you most likely just need to replace the thermostat.

The thermostat itself should be on a mounting bracket, from which it can be easily removed. Once removed, you can test if your thermostat is getting power. Make sure your multimeter is set to DC volts. Place your red probe on the positive and the black probe on the negative to see if you are getting 12V power to your thermostat. If it’s unclear which points are positive and negative refer to your thermostat’s manual.

If you got a voltage reading, that means you are getting electricity but that your thermostat is broken. It’s time to start shopping for a replacement.

Replacing Your RV Thermostat

After you’ve done your troubleshooting you’ve determined you need a new thermostat. So now it’s time to order a new one. There are quite a few options out there, depending on your budget, desires and your needs.

Be sure to read every detail of the product before ordering. We have found that some thermostats only fit in certain RVs. Also, some residential thermostats won’t work in your RV but I’ll cover that below.

Pricing ranges from the base models starting at a very reasonable $20, up to the most advanced ultra programmable models priced around $200.

Can you install a house thermostat model in your motorhome?

Yes, you can purchase a standard household thermostat but it must be battery operated. Household thermostats normally run on 24V AC power but RV thermostat runs on 12V DC. If it is battery operated, not just battery backup, then the thermostat uses the internal battery to power the display and relay not external incoming power.

How easy or difficult installing a standard house thermostat is will depend on your RV’s heat and air conditioning set up. You might have to spend some time sorting out how the wiring should be connected.

Certain types of RV thermostats must be replaced with the same model due to complex and different wiring. Also, if you have a dual speed air conditioner, you may also have to add an extra switch to control the air conditions different fan speeds or make sure you purchase a thermostat that has dual fan speed capability. So you might save a few dollars on the thermostat but spend hours figuring out how to install it.

How to Replace Your RV Thermostat

Though it may not feel like it right now, replacing your thermostat is a blessing in disguise. This is your opportunity to update that element of your system. You can even choose to upgrade as you update. Treat yourself to a deluxe digital read bluetooth capable model that makes your morning coffee and feeds the dog. Kidding about the coffee & pet care, of course.

Although it may not be the way you wish to spend your Saturday afternoon, changing out a broken thermostat in your RV may be a heck of a lot easier than you thought. After running through all of the testing steps listed above, you’ve found that you must replace your busted thermostat, so let’s get down to business.

Safety first. Shut off the power supply to the thermostat/HVAC by cutting off the batteries and unplugging shore power (or turning off the generator). Do this before you do anything else. The last thing you want is to injure yourself and/or your rig.

Refer to your manual as to how to remove your thermostat from the wall. Most will be attached to a mount, which is screwed into the wall. You have to pop off the cover and then unscrew the mount.

Once you have removed the old thermostat from the wall mount, take note of how the wires are run. You can even snap a photo for quick reference & label the wires for extra security. Disconnect all the wires from the back of the old system. When the wires are disconnected, you can then remove the mount itself. Save any hardware in a small dish.

Remove the new thermostat from its packaging. Give the manual a once over to see if there are any special installation instructions before continuing. Screw the new mounting bracket to the wall. Doing your best to get it in the same spot where the old one was. For any reason, if you have to change the position of the new thermostat, you may have to fill the old screw holes with a bit of spackle & top with paint.

Once your mounting bracket is securely in place, it’s time to get the wires hooked up to the new thermostat. Refer to the manual and back to your photo or notes on how the wires were connected to the old thermostat.

Hopefully, you’ve purchased a thermostat that is a direct replacement to the old one and there will be no funky wiring to figure out. Once wired, pop the cover onto your brand new thermostat and it should be ready to go.

Power your rig back up and test out your install. Your thermostat should be working properly and controlling your heat and air conditioning as expected. If it doesn’t power up make sure you didn’t miss replacing the fuse or forgot to install the battery. Otherwise, recheck your wiring.

At this point, you have successfully replaced your RV’s thermostat and are back to keep things frosty in the summer or toasty warm in fall. Unfortunately, not all of us can be so lucky that a simple like changing the thermostat will resolve your air conditioner or furnace issues. If you are still having problems it’s time to call in the professionals.

Why you should Upgrade Your RV Thermostat

Even if your thermostat is working perfectly, upgrading your existing thermostat to a programmable one is a great idea. For relatively few dollars you can add in some comforts of home with a nicely temperate RV.

RV manufacturers like to save money where ever possible and using an analog thermostat is just one of the ways they do this. Unfortunately, analog thermostats are terribly inaccurate and can be off by 10 degrees Fahrenheit making you have to constantly adjust the temperature to stay comfortable.

Another downside of really basic models is there is no “off” position for the thermostat so you have to pull the fuse to prevent the furnace from coming.

RV thermostat

Now you can buy a digital non-programable thermostat which will give you much more accurate temperature settings but you won’t have the added convenience of setting specific temperatures for certain times.

Changing your thermostat to a programmable one will let you set it and forget it, your temperature schedule that is. This is an awesome feature, especially if you tend to stay places for longer.

In cooler seasons, you can have the temperature adjust to be cooler at night, then turn up before you get out of bed in the morning. In warmer seasons you can have the air conditioning start cooling your rig during the hottest part of the day so you can return to a comfortable RV.

Unfortunately, there is no hard and fast run for which programmable thermostat you should buy since it depends on what you have installed currently. If you have a Coleman thermostat you will need to purchase a Coleman to replace it, the same goes for Dometic.

Make sure you do your research before going out and buying $100 thermostat only to find out it isn’t compatible with your system. Also, be aware that some thermostats are control heat only while others control heat and AC. It all depends on how your RV is configured.

Whether you pick a programmable or non-programable thermostat upgrading from your basic analog one will make a world of difference in keep your RV a more consistent temperature.

Diane Dee

Diane is a lover of all things travel. She and her young family wanted to explore North America from the comfort of their own home so they bought an RV. After fully rehabbing a 1994 Safari Trek, they set out to explore both Canada and the USA.

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