Duo Therm Thermostat Troubleshooting

Duo Therm Thermostat Troubleshooting: Issues and Fixes

We can imagine how annoying it’d be if your Duo-Therm Thermostat stopped working in the middle of a cold winter night or the summer heat. It makes things even worse if you’re on the road.

So, what do you do for damage control?

You try to find a way to fix it as fast as possible by looking up the internet for possible solutions. Now, you’ll find a lot of ways to approach this problem. But you need a quick fix.

Well, don’t worry. We are here to help you with exactly that and more. We have whipped up this quick fix guide on duo therm thermostat troubleshooting.

Here, we’ll answer the actual question; What do you need to fix? We have included the symptoms, the problems behind them, and ways how you can figure out and solve them.

So, before getting right into it, let’s check out what you’ll need for this.

Things You’ll Need

Fixing a thermostat can be quite a challenge. But the right handy tools can be a lifesaver in this case. Here’s a list of your lifesavers-

  • Soldering Iron
  • Solder
  • Small Flat Jeweller’s Screwdriver

Duo Therm Thermostat Troubleshooting

With every problem will come a way of diagnosing and solving it. So, you’ll need to read them carefully to get the job. Moreover, the complete troubleshooting won’t take much of your time.

So, without further ado, let’s get right into talking about the symptoms.

Symptom 1: Thermostat Won’t Turn On Or Stay On

This symptom indicates when your Duo Therm Thermostat won’t stay on or won’t start at all. It also includes when the AC units would turn off every time you hit a bump.

So, what might be the problem here?

You’ll find two main problems in this case. They are discussed in detail below:

Cracked Solder Joints

A lot of the time, the on/off switch has a cracked solder joint. This is what’s responsible for the Duo Therm Thermostat to show the symptom of not staying on. Let’s see how you can figure this out.


Open the Duo Therm Thermostat enclosure and set it aside. Now check the solder joints for any cracks. If you find any cracks, let’s see how to solve them.


Get the soldering iron and resolder the switch to the board. While doing so, make sure that the switch is a good fit on the circuit board. This makes sure that the solder won’t crack again.

Here’s a quick tip:

Use a small 25-watt soldering iron for this task. Moreover, it should have a finer tip on it. Make sure it’s an electric soldering iron and not the one used for plumbing.

Here are our recommendations:

Our Recommended soldering irons

Now, let’s move on to the next problem and try to solve it.

Cracked Trace

This symptom also happens to indicate a cracked trace in the circuit board sometimes. However, this can be fixed pretty quickly. Let’s see how you can do so.


Keep the enclosure open and check your circuit board carefully. Running your finger through the board will make it easier. If you find a crack or two, let’s see how we can solve that.


Carefully scrape the green backing off the board with a small razor knife. Now solder a small piece of solid wire across the crack. The wire can be something like a telephone wire.

That’s all for the symptom of your Duo Therm Thermostat not staying on. If this is not the one, let’s move to the next one.

Symptom-2: Push Buttons Not Working

Issues with buttons are more common than you would think. You might be pushing on the buttons, which aren’t working like they’re supposed to. This symptom is usually associated with dust accumulation beneath the button.

Accumulated Dust

Since your RV is on the road a lot, your thermostat board might store dust in different spots. Now, if dust accumulates beneath the pushbuttons, they’ll not work. Let’s solve this.


Start by opening the thermostat and checking the rubbers below the push buttons for dust. Now, check the other areas as well and start cleaning.


Clean the switches first and once you’re done with that, remove the PC board from its housing.

Now, use a small flat jeweler’s screwdriver to carefully prise the tabs holding the top of the switch on the base.

Clean the contacts with spray contact cleaner and perhaps Q-tips. Once all that’s handled, snap the top back on the switch. That should fix your pushbuttons.

Moving on, let’s discuss the last symptom on our list.

Symptom-3: AC Cooling at Wrong Temperature

It’s the symptom where your AC unit doesn’t work at the right temperature. Now, this is a hard one. But we have included everything that you’ll need to solve this by yourself.

Temperature Sensing Error

If your AC unit is not cooling at the right temperature, then the problem behind it is a temperature sensing error. This is hard to solve because of its complexity, but you can try.


Take a thermometer and run it around the house to check your room temperature before the Duo Therm Thermostat starts working. Now, take another temperature reading when it stops.

Now check the temperatures. They are supposed to have an accuracy of +/- 3 Degrees Fahrenheit. If the temperature is further off, try the solution mentioned next.


Here’s what you can try to solve this problem:

  • Turn the thermostat off. Turn the AC on and off. Now, turn the thermostat on again.
  • Perform a factory reset.

Now, here are some AC unit-specific probable solutions to help you out further:

[su_table responsive=”yes” alternate=”yes” fixed=”no” class=””]

AC Unit Type Solution
Rear Unit Get a new upper board
Front Unit Without Remote Sensor Install Remote Sensor
Front Unit With Remote Sensor Check With Ohmmeter and Replace Thermistor Sensor and/or Upper Board



We know how pesky a malfunctioning RV Thermostat can be when you’re out vacationing. You might be just cruising in your RV as well. But, that’s not how it should be.

That’s why we tried to help you with this Duo Therm Thermostat Troubleshooting Guide. Try to follow the whole guide carefully. And don’t take risks when it comes to electrical work.

That’s all from our side now. If you have anything that you want to tell us, let us know in the comments.

Drive safe and stay healthy.

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