Window Air Conditioner Thermostat Troubleshooting (7-Step Guide)

So often, a safety thermostat is why a window air conditioner won’t cool, heat, run continuously, or even turn on. But did you know that the window air conditioner thermostat troubleshooting is often DIY? 

Start by checking the thermostat’s temperature and set it accordingly. Then clean the AC, reset the breaker (if tripped) and replace the fuse (if blown up). Lastly, check for dead batteries, bad wiring, a faulty sensor, or incorrect installation.

Note, however, that while this is a 7-step troubleshooting guide, you may fix your thermostat in any step, including the first. So, you don’t have to get to step 7 once your air con thermostat starts working.

To help you, I’ll describe the steps chronologically to help you get started with the troubleshooting. But before I do, I’ll discuss the signs or problems associated with a failing window AC thermostat. 

Let’s get into it! 

window air conditioner thermostat troubleshooting

In a rush? Below is a quick guide to fixing your non-working window AC thermostat

Quick Window Air Conditioner Thermostat Troubleshooting Guide

What To Check (Possible Cause)Quick Fix
1.Incorrect Temperature SettingSet the thermostat on Cool, or Max Cool mode, deactivate Child Lock and adjust the temperature setting
2.Dirty UnitClean the air filter, coils, and thermostat, preferably with paper towels
3.Tripped Breaker Or Burnt FuseReset the breaker if it’s off, and replace the fuse if it’s  burnt (it has no continuity)
4.Dead Batteries Replace the remote control’s batteries if they are dead
5.Bad WiringFix any loose or faulty wiring or ask for a technician’s help
6.Faulty Sensors Replace the thermostat sensor if it’s faulty (lacks continuity)
7.Incorrect InstallationRe-install a dislodged thermostat

Window Air Conditioner Thermostat Problems (Signs of A Bad AC Thermostat)

A failed window AC thermostat is easily detectable when using the unit. So, whenever you notice the signs, there is a chance the thermostat might be misbehaving or probably broken down.

The problems or signs in question include the following:

1. Window Air Conditioner Not Turning On

While there are different reasons why a window air conditioner won’t turn on, one of them is a faulty thermostat. If the thermostat is broken or shorted, it will prevent the air conditioner from starting. Remember that the wrong thermostat setting can prevent the AC from turning.

2. Window Air Conditioner Not Cooling

A faulty thermostat can also prevent an air conditioner from cooling. Sometimes, however, the AC won’t cool, not because the thermostat is defective but due to the wrong setting.

For example, setting the thermostat on ‘Heat Mode’ will heat and not cool. But as far as a faulty thermostat goes, check for signs of breakage and poor installation. They could be the reason the window AC won’t cool.

See also  10 Reasons LG Portable Air Conditioner Not Blowing Cold.

3. Window Air Conditioner Not Heating

Just like a faulty or incorrectly set thermostat will result in a non-cooling window AC, it’ll equally result in a non-heating one. For example, the AC won’t heat if the thermostat is on ‘Cool Mode.’

That, however, doesn’t mean the window AC is faulty. You can tell a faulty AC if you can’t adjust the temperature.

4. Window Air Conditioner Running Continuously 

The thermostat typically signals the window AC to turn off once it reaches a specific temperature. That, however, won’t happen if the thermostat is faulty.

Instead, your air con will continuously run until you power it off and fix the thermostat (or replace it).

5. Window Air Conditioner Not Reaching a Room Temperature

The thermostat should operate at a summer temperature of about 25.50C or a winter temperature of 20 – 220C. That, however, won’t be the case if the thermostat is defective. 

It’ll have difficulty reaching that temperature limit once you preset it. So, the window air-con may blow very cold or hot once the thermostat malfunctions.

6. Shorter Air Conditioner Cycles

Lastly, a faulty thermostat could cause your window air conditioner to run shorter cycles. That is odd and leads to costly energy bills, something to avoid.

window air conditioner thermostat problems

7 Window Air Conditioner Thermostat Troubleshooting Steps

Now that you recognize the signs of a failing thermostat, here are seven steps to get it working:

Step 1 – Check and Set the Temperature Correctly (Window Air Conditioner Thermostat Adjustment)

Unless the temperature is set correctly, an air conditioner’s thermostat won’t work. So, this is an important check.

First, ensure the window AC is in Cool or Max Cool mode. After that, ensure that the setting is as low as possible. 

Also, turn off Child Lock (CL) if it’s on. Doing that shouldn’t get the thermostat working if the issue was the setting. If it doesn’t, then you should adjust the thermostat using these simple steps:

  • Turn the AC on if it’s off by pressing the ON/OFF switch
  • Wait for the air conditioner to start and display the temperature
  • If it doesn’t, press ‘Mode’ and wait for it to beep and display the temperature
  • Then use the up/down arrows on the front panel or remote control to either lower or raise the temperature

Step 2 – Clean The Air Conditioner (Especially The Filter And Coils)

Too much debris, dust, or dirt blocks the filter and coils, causing the thermostat to start misbehaving. It is unable to run normally, resulting in cooling and heating issues. So, you must inspect the unit, especially the filter and coils, for dirty clogging and clean them.

See also  Can RV Air Conditioner Run Continuously? Find Out Here!

Also, clean the thermostat, which you can locate beneath the front cover. You can use a paper towel to do it.

Step 3 – Look for A Tripped Breaker or Burnt Fuse

If your window air conditioner or the thermostat doesn’t turn on, the problem could be a power failure due to a tripped breaker or burnt fuse. The breaker will likely fall/trip when the AC experiences a current overload.

The same goes for a burnt fuse. So, check them. If the breaker is tripped/off, reset it. `

As for the thermal fuse, you’ll need to test it with a continuity tester (multimeter). An absence of meaningful continuity suggests the fuse is bad and requires replacement.

Step 4 – Change the Remote Controls Batteries

Sometimes, the cause of the window air conditioner thermostat not working could be the remote control and not the air con. If the remote control doesn’t turn on the AC, the thermostat won’t work.

So, start by replacing the remote control battery, especially if it has been a while since doing so. And while replacing them, ensure you install the fresh pair correctly according to polarity.

Step 5 – Identify Any Bad Wiring

If there’s a problem with the thermostat’s wiring, the thermostat will malfunction. So, it’s worth checking the wires for loose connections, breakages, detachments, and corrosion.

That means you must locate the thermostat beneath the front panel to inspect it. But if you can’t do it, call an HVAC technician to handle this step and the other remaining two, depending on the problem.

window air conditioner thermostat adjustment

Step 6 – Inspect The Thermostat Sensor

The thermostat has a sensor that dictates its running. If the sensor is defective, the thermostat may turn on and off irregularly or fail to switch on/off entirely.

So, when you notice such signs, inspect the thermostat sensor. Use your manual to locate the thermostat sensor and check for loose connections or bending.

You can also examine it with a multitester/multimeter, and if it doesn’t show continuity, replace it, as that proves it’s defective.

Step 7 – Check for Poor Installation

Lastly, if you still can’t troubleshoot the window AC thermostat up to this point, consider checking its installation. If the installation is poor, the thermostat won’t work.

In particular, check to see if the thermostat is dislodged. If it is, uninstall it, then re-install it correctly.

How to Bypass Thermostat On Window Air Conditioner?

If your window air conditioner is old, you may choose to run it as soon as you supply it with power and not when the thermostat wants to run. In that case, you get to bypass the thermostat, and here is a procedure for doing it:

  • Switch off your air-con
  • Remove the panel cover or the control panel (depending on the model) to access the thermostat
  • Cut the wire going to the thermostat and the one leaving it
  • Connect the two wires to complete a circuit without the thermostat
  • Now you can run the AC without the thermostat
See also  Samsung Air Conditioner Troubleshooting Manual and Guide

How to Reset a Window Air Conditioner Thermostat?

You can reset your window air conditioner thermostat by resetting the whole unit. Here’s how to do it:

  • Press the reset button (if it’s there) and hold it for 5 seconds
  • If the reset button is absent, unplug the AC for 20 minutes.

Remember, the above reset procedure reverts the air conditioner to its default/factory settings

How to Replace Thermostat in Window Air Conditioner?

Generally, you can replace most window air conditioners using these steps:

  • Unplug the window air con from the power socket
  • Pull it out of your window. You may need to unscrew it if that’s applicable and set it aside
  • Pull out the front panel and then the air filter (you can inspect the air filter for dirt clogging and clean it)
  • Now take out the control panel (you may need to unscrew it)
  • Access the thermostat and unscrew it
  • Install the replacement thermostat and screw it in position
  • Return everything else as they were
how to replace thermostat in window air conditioner

People Also Ask

1. How Do You Reset the Thermostat On a Window Air Conditioner?

Some window air conditioners have a reset button that you can press for about 5 seconds to reset the thermostat. For those that lack the reset button, consider unplugging them for about 20 minutes. You can also reset the breaker for the same period (20 minutes).

2. Where Is the Thermostat On a Window AC?

In most cases, you can find the window AC’s thermostat beneath the front or control panel.

3. Why Won’t My Air Conditioner Respond to My Thermostat?

Your air conditioner is not responding to the thermostat because of an issue like a dirt-clogged filter, power failure, or wrong setting. The remote control could also be a problem if its batteries are dead.

4. How Does the Thermostat Work On a Window Air Conditioner?

An increase in room temperature triggers the air conditioner’s thermostat, which causes the blower to run. Once the blower runs, the air conditioner cools the warm air that passes through the cold coils and cools down your room.

Closing Thought On Window Air Conditioner Thermostat Troubleshooting:

Above is a guide to consider when you suspect a window ac thermostat malfunction. As shared, if your AC won’t cool, turn on, heat, stop or run a regular cycle, it’s likely the thermostat is faulty. If so, you should fix it – at times involving replacing it!

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