RV Thermostat Troubleshooting

The thermostat in your RV tells your system whether it needs to heat or cool the inside. However, if your system seems to have a life of its own or isn’t functioning as efficiently as it should, examine the thermostat since it may have gone bad.

It can take a long time to find the problem, and it could be in the most unlikely of locations.

A system reset option may help, but sometimes the most straightforward stuff is the source of the problem. Look at your fuses, particularly the ones under your RV’s roof, to figure out what’s wrong. Then, if there is a blown fuse, replace it, and you should be ready.


In our guide, you can learn more about Dometic thermostat troubleshooting without having to pour over the owner’s manual.

By the end, you’ll be able to deal with most thermostats as the same problem can hit them all. At least you’ll know what to do to have your Duo Therm Comfort Control up and running in the shortest possible time. (Learn DIY RV Outdoor Shower Enclosure)

How Do I Test My RV Thermostat?

Follow the steps below if you’re having HVAC system problems with a Dometic RV thermostat or need to troubleshoot a Coleman Mach RV Thermostat, as the same issue can fall on both models.

battery failure

Battery Failure

  • Modern digital thermostats require batteries to operate the control unit.
  • It’s smart to replace the batteries and re-check all the broken features.
  • But a fully exhausted battery also makes the thermostat appear dead.
  • Look at the digital display screen. It should glow, yet if the backlight or sidelight is faint, the internal bulbs may have failed or are failing.
  • A blank screen shows the thermostat is not providing data to the screen. It might be a screen failure.

Circuit Breakers

It’s simple to find your furnace heating and cooling circuit tripping silently. You won’t know unless you double-check.

If one or more have tripped, reset them and check the thermostat and related equipment. While it may be okay with cooling, they can easily trip when the furnace kicks in for heat, and you need more power.

Thermostat Position

An RV thermostat could be in a place where it shows the RV thermostat is bad. However, it is the direct sun shining on your RV thermostat panel. Alternatively, any flaws or gaps beneath the thermostat could allow cooler air to infiltrate and alter the readings.

Both scenarios have the potential to change the thermostat’s internal temperature and make it appear you have a bad thermostat, resulting in erroneous results.

How Do I Reset My Dometic thermostat?

One of the critical things you can go through is resetting your RV air conditioner before you replace things in your furnace or checking the wires. The same thing can happen for errors, and a system reset can easily reset things to how they should be.

It could be nothing more than the settings that stop your RV AC unit from cooling, and you have a blank screen.

Here are the detailed instructions for how to hard reset your Dometic RV Air conditioner control systems and make sure it runs at the right temperature.

  • Press either the “+” or “―” button which enables you to change temperature set-point. You see the temperature set-point displayed in two digits on the LCD screen.
  • Press the “+” button so you can increase and the “―” so you can decrease the temperature set-point. You can discover, the maximum set-point for your system is 90º F, and the active operating mode will determine the minimum set-point.

Heating has a minimum of 40º F. The minimum you can set for cooling is 55º F.

“Off” – Off Mode

When you select this, the LCD will be blank, and the Off green LED will turn on for 15 seconds, then it will turn off.

“Cool” – Cool Mode

The system cycles the compressor On and Off according to the room air temperature and the temperature set-point shown on the Single Zone LCD thermostat in Cool air mode.

The fan turns on first and is followed by the compressor after around 2 -minutes. Here, you can find 3 fan speed selections:

  • Lo – (LOW): Your fan operates at low speed as the compressor cycles ON and OFF.
  • Hi – (HIGH): The blower motor and fan operates at high speed as the compressor cycles ON and OFF.
  • Au – (AUTO): When the auto fan is selected, the fan speed varies based on any difference between the temperature set-point and the room air temperature. In this auto fan mode, the compressor and fan cycle On and Off using the thermostat.

How Do I Know If My Thermostat is Bad?

Here are a few things to check to see if your thermostat is working properly or how to tell if RV thermostat is bad?

1. Lack of Power

The most typical problem with thermostats is that they lose power and refuse to turn on. The RV thermostat wiring may have become disconnected from the RV’s electrical system in this situation. The thermostat wiring could be slack, causing the unit to disengage during transit.

When you tweak the settings on your RV thermostat, you may notice that the temperature does not change. As a result, the thermostat cannot detect the current room temperature, resulting in the unit operating inefficiently.

You may also notice that the thermostat’s display is faint or that it does not turn on at all. It’s possible that the screen has been damaged, resulting in the unit malfunction and make it impossible to change the temperature setting.

Some battery-operated RV thermostats are available. If you’re sure the problem isn’t with your electrical system, it could be a problem with the unit’s batteries. Replacing the battery is a simple procedure that does not need the services of a specialist.

If you change the battery and the thermostat still doesn’t work, it may be broken. Thermostats that are damaged, broken or unresponsive should be replaced with new ones.

Buying a refurbished thermostat is a bad idea. While they may be less expensive than buying a new unit, they rarely come with a warranty, and there is a danger that they will break down.

Always purchase a new thermostat, be it from the AC manufacturer or a reputable agent. A new programmable thermostat unit comes with a warranty and makes life much easier.

2. The AC or Your Heater Doesn’t Turn On

If the thermostat is not receiving electricity, it could be due to wiring issues or dead batteries in the unit. Due to wiring difficulties, the unit cannot send and receive the electrical impulses it needs to function correctly.

You’ll need to take the thermostat out of the casing and look for any damage to the wiring. You can take the unit to a professional electrician for testing if there is no visible damage to the wiring or harness.

3. Your Heater Runs Continuously

If your heater or air unit is always running and won’t turn off even when you hit the power button, it could be due to frayed wiring or a thermostat unit that isn’t appropriately calibrated.

You’ll also need to remove a few screws, then the unit, and inspect the wiring harness in this scenario. Take the unit to a competent electrician for an assessment and inspection if the wiring appears to be in good condition.

4. Settings Don’t Match the Actual Temperature

One of the subtle symptoms that your RV’s thermostat is on the fritz is the actual temperature felt different from the readout on the thermostat. If the heater is turned up, but the temperature inside the RV does not change, the unit may need to be re-calibrated.


How Do I Fix An Unresponsive Thermostat?

We’ll look at RV AC thermostat troubleshooting problems with your HVAC system and thermostat here.

You’ll find a few other factors that can go wrong, yet here you’ll find the most common fixes to make your RV thermostat work as it should.

If you notice any of the above telltale indicators with your RV’s thermostat and air-conditioning system, run through the following thermostat troubleshooting suggestions, and get your RV thermostat to work correctly. (Read AC Fan Not Turning On – What to Do)

1. Make Sure Your Thermostat is On The Correct Setting

This procedure may seem self-evident to most RV owners. If it’s winter, make sure the thermostat is set to warm; if it’s summer, make sure the thermostat is set to cool.

Simple errors can lead to significant issues, especially if this is your first RV and you have no prior expertise working on these vehicles.

If your heater or air unit runs continually, it’s most likely because the setting is “On.” Locate the thermostat’s control panel and set it to the “Auto” setting. The temperature is automatically adjusted to fit your preferred operating conditions.

The air conditioner or heater only blows air in the auto mode when the system is heating or cooling the air within the RV.

2. Adjust Your Thermostat Up or Down by 5 Degrees

Set the temperature to 5-degrees lower than the outside air temperature if you’re suffering from this problem in the summer. In the winter, however, set the thermostat to 5 degrees warmer than the outside temperature.

A clicking sound should be heard while changing the thermostat settings up or down. After a few minutes, check the cooling system and the supply register vents are blowing or sucking in air from inside the RV.

3. Check and Replace Thermostat Batteries

Digital RV thermostats are included in many modern RVs, so consider replacing the batteries if you have a digital thermostat in your RV. If this is the case, you’ll see the thermostat spring into life.

If the batteries are replaced, and nothing happens, the wiring should be the next step in troubleshooting. If your RV has a digital thermostat, it’s a smart option to replace the batteries once a year to avoid dealing with a broken thermostat.

Note, you can’t change RV thermostats with household thermostats. They run on AC power and use batteries for backup and not for DC volts power.

4. Blast Your Thermostat with Air

Mechanical thermostats are included in specific older RV model cooling systems. A mechanical thermostat may usually be identified by a little lever that allows you to change the temperature within the RV. Mechanical thermostats are prone to dust collection. Dust might get inside the unit and clog up the mechanical components.

If you buy a used RV with a mechanical thermostat, this could be the issue that’s causing the unit to break down. Remove the unit’s cover and clean it with compressed air from a can.

5. Test Your Wires and Connections

If you’ve gone through the RV thermostat troubleshooting tips above and your thermostat is still not working, it’s time to look at the wiring. If you do not know of electrical components, we recommend you use a professional electrician. (Find the Best Portable AC For RV)

Remove the lid of the thermostat and inspect the wiring connections onto the circuit board if you have electrical experience. If there is any old wiring or loose wires, reconnect them and see if it makes a difference to the digital display and your heating and cooling equipment.

RV Thermostat Troubleshooting (1)

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