Where Is A Dometic RV Air Conditioner Thermistor Located?

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Knowing where to find your Dometic RV air conditioner thermistor is essential to maintaining your air conditioning system. If you're wondering where the thermistor is located in a Dometic RV air conditioner, then you're in luck. We have the answer below!

Dometic's RV air conditioners have a thermistor located in the evaporator coil. Just look for a wire that has a plastic connector that connects the control board to the evaporator coil.

A thermistor is responsible for monitoring and regulating the temperature at an ideal level. As such, you must know where to find this component so you can easily replace it whenever it fails. Continue reading as we show you the common symptoms of a bad thermistor and the steps to replace it.

Common Symptoms Of A Bad Thermistor

When your thermistor starts to fail, you may notice strange behaviors from your air conditioning system. Thermistors can fail for various reasons, but the most common cause of failure is prolonged exposure to high temperatures.

Here are a couple of symptoms of a bad thermistor:

False Temperature Readings

If the thermistor is damaged or broken, it may no longer send accurate signals to the control board.

If this happens, the air conditioner's flow rate calculation will likely be inaccurate, resulting in the air conditioner giving false readings.

Temperature Fluctuations

This thermistor measures the temperature of the evaporator coil and relays this information to the control board. If the thermistor becomes faulty, the A/C compressor can no longer regulate the cooling capacity to match the ambient air temperature.

This causes the system to make wild guesses instead of using the gathered data from the evaporator coils.

How To Replace A Dometic RV Air Conditioner Thermistor

Replacing a Dometic RV air conditioner thermistor is a common do-it-yourself project that anyone can complete. Here are the tools that you need.

Tools that you need to replace a dometic rv air conditioner thermostat, Where Is A Dometic RV Air Conditioner Thermistor Located?

  • A needle-nose plier
  • A 5/16 socket wrench
  • A quarter-inch socket wrench

Once you have your supplies, you can start the replacement process:

1. Disconnect the air conditioner

The first step is to turn off the power to the air conditioning unit. You can disconnect the power by turning off the switch and unplugging it from the wall outlet.

2. Remove the evaporator coil cover

Next, remove the plastic cover from the top of the evaporator coil housing.

You can use need-nose pliers to loosen the screws. After removing the cover, you should see the thermistor, as it's the only component that protrudes from the aluminum fins.

3. Remove the thermistor

Gently pull one end of the thermistor out of the aluminum fins. Don't pull the other end connected to the control board yet.

4. Install the new thermistor

A technician install the new thermistor in modern electronic device

The flat end of the thermistor should go between the aluminum fins. Check the instructions on the label as to the proper spacing.

5. Remove the cover of the control board

Using a 5/16 socket and a quarter-inch socket, remove the bolts that hold the control board cover in place. Remove the cover.

Check out this socket tool set on Amazon.

6. Loosen the cables to release the old thermistor

You'll see a bunch of cables bundled together and attached to the control board.

Using a needle-nose plier, squeeze the bundled cables through the tab that holds them in place until you can create enough space to release the thermistor.

The cable with a 2-pin connector is the one you want to release. Once you have enough space to get the cable through, you can pull it out from the control board by grabbing the base of the connector.

Check out this needle-nose plier on Amazon.

7. Connect the other end of the thermistor to the control board

Complete the installation by connecting the control board's other end of the thermistor (2-pin connector).

8. Put everything back together

Follow the steps in reverse order and reassemble the unit. Start with the control board cover and the evaporator coil plastic housing cover.

What Causes Thermistors To Fail?

Like many electronic components, the thermistor is susceptible to failure and is affected by many factors.

The thermostat is only one piece of the equation: the rest of the parts, like the control unit, the wiring, and the heating and cooling unit itself, must also function correctly.

If any of these parts malfunction, it can cause problems with the thermistor and, thus, the entire system.

Here are some of the more common causes of thermistor failures:

Improper Installation

To function correctly, a thermistor must be installed in the correct orientation.

The flat end of the Dometic RV air conditioner thermistor should be placed at a certain angle and placement between the aluminum fins as indicated in the manual.

If the flat end of the thermistor is anywhere not close to the ideal placement, the thermostat may not detect the temperature accurately. This will cause the air conditioner to work incorrectly.

Thermal Mismatch

Thermistors are sensitive to temperature changes that occur due to changes in external conditions.

One of the most common problems is thermal mismatches, where there is a change in ambient temperature and a difference in the internal temperature.

For example, if there is an increase in the external temperature, but the internal temperature stays the same, there will be a difference in the temperature readings taken by a thermistor.

In this case, the resistance does not change when the external ambient temperature changes. This causes the air conditioner to be stuck in a particular state, which will not allow it to function correctly.

Ideally, a thermistor should be able to automatically adjust its temperature settings based on the actual temperatures that it measures within your RV.

Heat Damage

The most common failure mode for thermistors is overheating. Clogged air filters, dirty condenser coils, and a leaking refrigerant can cause this.

When this happens, the thermistor's resistance continues to decrease to the point that it will cause a short circuit.

The result is that the thermistor cannot shut the air conditioner off at the correct temperature, and the air conditioner continues to heat up.

Is A Thermistor The Same As A Thermostat?

A thermostat can be equipped with a thermistor. However, the thermistor that a typical thermostat has may not be as sensitive as the true thermistor that you connect to the control board of your Dometic RV air conditioner.

Thermistors are often confused with thermostats because they're both temperature sensors and measure temperature. But there are some key technical differences.

While a thermostat can measure temperature directly and is the traditional control method, a thermistor is far more reliable.

What Makes A Thermistor More Reliable Than An Ordinary Thermostat?

Thermistors are also better at sensing the temperature in various conditions. They utilize resistors to measure temperatures, which are much more accurate than the direct measurement of a thermostat.

The difference in temperature reading may not be substantial. Still, thermistors are designed to read the temperature level as sensitively and accurately as possible so that the air conditioning system can respond accordingly.

How Much Does It Cost To Replace A Dometic RV Air Conditioner Thermistor?

Cooler thermistor air temperature sensor

Thermistor replacement is usually straightforward and requires little more than removing a couple of housing covers, the faulty thermistor, and installing the new one.

The thermistors in a Dometic air conditioner are usually housed in the air conditioning unit itself, making it easy to access and replace.

You can DIY the replacement of a Dometic RV air conditioner thermistor, and it will cost you only the thermistor for $25 on average.

Can I Use Any Kind Of Thermistor For My Dometic RV Air Conditioner?

Guy holding electronic parts with his hand

A general rule is that any thermistor manufactured by a certain brand will work with the rest of that brand's line of products.

While thermistors are generally compatible with the same brand, you'll need to find the exact type to replace your current thermistor.

This means you'll have to figure out the exact part number of the thermistor. You'll usually find this info in the user's manual.

Can You Repair A Broken Thermistor?

You can always choose to repair a broken thermistor. This means you will have to undergo some troubleshooting to figure out the cause of the problem.

Check both ends of the thermistor for resistance using a multimeter.

If any or both ends read zero, you have a bad thermistor. You can snip the end where the problem is and solder the replacement piece (either the 2-pin connector or the flat-head metal piece).

Can I Submerge A Thermistor In Water?

One end of the Dometic RV air conditioner thermistor is placed in a location where it will come in contact with a good amount of moisture while the other is in the control board.

It just makes sense to logically assume that only one end of the thermistor with the flat end is designed to be water-resistant.

How Long Do Thermistors Last?

The typical lifespan of a thermistor is about three years. As the thermistors age, their ability to accurately measure the temperature in the RV diminishes.

Another factor that affects the life of the thermistor is dust.

Dust buildup in the air conditioning system can cause overheating, which in turn shortens the lifespan of the thermistor. All of these can lead to inaccurate readings and potentially unsafe conditions.

In Closing

Air conditioner spare parts thermistor

It's not hard to figure out where the thermistor in a Dometic RV air conditioner is located. You need to know where in your Dometic RV air conditioner you can find the thermistor so you can quickly replace it when it fails.

We also provided easy-to-follow steps to replace it if you need to. A failed thermistor can lead to dangerous conditions inside your RV. It can even result in costly repairs and expenses.

Made it to the end? Check out these helpful related posts:

Do Digital Thermostats Have To Be Level?

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