Window air conditioner thermostat troubleshooting: How to fix common problems yourself

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Your window AC thermostat behaving strangely? This window air conditioner thermostat troubleshooting could come in handy…

You should expect your window air conditioner thermostat to last about 10 years (without breaking down) but many window air conditioner thermostats may develop faults earlier.

Fortunately, most of the minor issues can quickly be fixed with straightforward repairs.

To help you make your thermostat (and air conditioning unit) work again, below we show you how to do simple and intermediate window AC thermostat repairs, plus those a few that are more demanding and could need a little bit more skill.

Of course, on the whole, DIY troubleshooting is cheaper and more convenient so we urge you to take a crack at the repairs we explain below.

Window air conditioner thermostat troubleshooting: How do I fix my window air conditioner thermostat?

If your internal window air conditioner thermostat seems like it is having a mind of its own, here is what you should try.

Thermostat gummed up with lots of debris and dust and won’t read the temperature right? Clean it thoroughly

Dirt is likely to cause your thermostat to start operating incorrectly and could be the primary culprit if your window air conditioner thermostat is malfunctioning.

That being so, you can commence your troubleshooting by checking and cleaning it, if necessary.

Where is aircon thermostat (window units)?

As regards your aircon thermostat location, the thermostat is typically accessed after removing the front cover (of your AC).

For that reason, start by removing the front cover.

How to clean window ac thermostat

Now, for the most part, the thermostat is simply a wire that runs at the base of your AC and into the middle of your coils (look for a wire that is covered in rubber sleeve).

Go ahead and remove the wire (do not pull out the plug as you don’t want to mess with anything else).

Next:

  • Take a paper towel and run it along the wire length of the thermostat while wiping it (recall that the thermostat is oftentimes a copper tube that is about 3 to 4 inches long).
  • Replace the thermostat- check that it is not leaning up against the inside of the unit in any way (it should be hanging free).

Window ac thermostat not working no matter what you try? Try the following

Besides dirt (and you already know what to do), a couple of other issues could be upsetting things causing your air conditioner thermostat problems.

Try these hacks:

Basic step

Before going any further, ensure you have set the ac to cool (max cool setting). Plus, your window ac thermostat setting should be set low enough (set it as low as it is able to go).

If that doesn’t help, go ahead and try the following…

Inspect the wires

If, for one reason or another, the thermostat wiring has gotten frayed or all screwed up, it might be worth inspecting the wiring and fix appropriately.

Check if the thermostat sensor is working

Another probability is that of your window ac thermostat sensor not working.

Now, the main pointer to a defective temperature sensor is erratic cycling on/off (the thermostat starts to switch on/or off irregularly).

To try and remedy the situation, locate the sensor (check your owner’s manual if not sure about its placement) and check if it might be bent and in direct contact with the evaporator coils (it is usually placed near evaporator coils).

If so, put it back in place correctly.

Also, fix any loose connections to the sensor.

Lastly, you can test it with a multi-meter to see if it’s actually working.

Thermostat dislodged? Re-install it properly
Don’t forget to check also if the thermostat may itself have become dislodged as well- it can, for example, during the process of taking out the cover.

That may cause it to start touching the coil (or other parts of the unit) leading to improper operation.

The fix is again removing the front cover and re-installing the thermostat the right way.

How do you reset the thermostat on a window air conditioner?

Simply reset your entire window AC unit- doing so resets everything including the thermostat and it can clear some of the tough-to-diagnose issues.

You can reset your window AC by turning it off then turning it back on after about 20 minutes.

Alternatively, you can reset the unit by pressing your window air conditioner reset button then waiting 5 seconds especially for newer models- some feature a reset button.

Either way, the thermostat is likely to go back to its default settings.

Try this if everything else we have covered in this window air conditioner thermostat troubleshooting guide has not worked.

Window air conditioner thermostat troubleshooting – frequently asked questions [FAQs]

How do I know if my AC thermostat is bad?

But what if your thermostat is broken- how can you tell?

Well, you can check your tstat for continuity using a multi-meter.

Besides, you can try this:

With your AC unit off turn up and down the temperature adjustment while listening for a click- if you hear the “click” sound, it means the relays in your stat are functional.

Obviously, it may be faulty if you don’t hear a click sound.

So, how do you replace it with a new one if it is dead?

Watch this video for the general replacement steps.

How do you bypass a window air conditioner thermostat?
If you want your old A/C to run the entire time when power is supplied to the unit (and not when your t/stat wants), try the procedure below:

Window air conditioner thermostat bypass – procedure

  1. Turn off the unit.
  2. Access the thermostat by removing the cover (it is may be necessary to remove the control panel first in some models).
  3. Cut the wire that is going in as well as the wire that is going out then connect them together.

This is probably the easiest way of taking the tstat out of the loop!

How do you trick an AC thermostat?

To trick window ac thermostat and make it falsely believe it is too warm:

  1. Place a heat pad/hot water bottle near the AC OR
  2. Put an incandescent bulb (a 60/100w bulb may suffice) close to the unit.

That way, the AC may work harder.

 

What next?

If you have tried all the above, you’re potentially out of luck and it could be time to call a HVAC professional for advanced diagnosis.

FURTHER READING:

How to use air conditioner effectively [simple hacks and fixes]

Does portable air conditioner need to be vented outside?

GE Window Air Conditioner Troubleshooting [step-by-step guide]

How to reset Frigidaire window air conditioner [step-by-step]

 

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