How to Fix a Broken Aircon Thermostat?

A broken Aircon thermostat can become a headache on summer days and needs a quick repair. We depend on the thermostats in air conditioning systems to provide us with correct temperature readings and ensure the required adjustments. If the thermostat does not work correctly, you cannot effectively communicate with your system to achieve your comfort levels.

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A broken or damaged thermostat is an immense problem and is none less than an annoyance. Without you realizing it, your entire room or home could get teasingly cold or hot. Simultaneously, it could also lead to energy loss; given the energy costs today, this is something that you would not like to happen. Hence, grabbing the problems and resolving a broken thermostat is essential.

Indications of a Broken or Damaged Thermostat

Thermostats in most aircon are set inside the unit. We cannot tell from the outside whether the thermostat is broken or damaged. Therefore, we rely on some indications that the aircon will give when the thermostat is damaged. 

  1. The thermostat’s display shuts off and does not turn on again. It is evident that when the thermostat is damaged, it will not display anything on the screen.
  2. Because the thermostat is responsible for communicating with the aircon to maintain the desired temperature, the aircon will not hold the desired temperature if the thermostat does not work correctly.
  3. The aircon system remains confused about which we need our system to cut.
  4. If your aircon does not turn on, it indicates an issue with its thermostat. Other problems can also stop the system from turning on, but a broken aircon thermostat is the fundamental reason. 
  5. When your aircon unit does not turn off when required, it points out a potential thermostat failure.

What Happens with a Thermostat? And How to Fix it?

Thermostats can encounter specific issues that are hard to deal with from outside the unit. On checking it, you know that the fault entirely lies in the broken thermostat. While hiring a professional is the best, you may consider resolving the issue independently. Fixing a thermostat is one of the do-it-yourself tasks that will save you repair fees if the following steps are followed:

Remove the Faulty Thermostat

First, dismount the faceplate covering the thermostat by hand. As you loosen the mounting screws to dismount the thermostat from the wall, check that no single screw gets lost. Also, ensure that the wires attached to the thermostat don’t lie between the walls. Grip them with one hand as you remove the screws with the other hand.

Fix the Wires

While fixing the replacement thermostat, connect the wires correctly. Ensure the wires are fully clean. Ensure the new thermostat matches its voltage and electrical rating with the faulty one. If a thermostat is incompatible with the heating system, its performance is affected big time once you have installed the new thermostat; tape up all openings to stop cold air from entering the inside walls since it may affect the thermostat’s performance.

Check the Settings

This is an important check, and if you have set up your thermostat to cool mode and it works exactly the opposite, it indicates the settings issues.

The thermostat should be set to “auto” to ensure that your aircon unit works smartly and in an energy-efficient way. 

Check the Batteries

The most common reason broken aircon thermostats are not working is that the batteries are dead. If the batteries in the thermostat do not work correctly, the thermostat will not be functional. You will then need to replace the batteries in the thermostat. If the thermostat is still not working.

How to Fix a Broken Aircon Thermostat

Electric Thermostats

It would help if you always tried checking the power source/batteries in new electronic thermostats. If this method helps, your aircon is OK, and vice versa. 

Mechanical Thermostats

If your thermostat contains a small lever for moving the temperature, it indicates that you have a mechanical thermostat. These devices might not work correctly over time due to dust. Remove the thermostat cover and use a cloth or small brush to remove the dust inside.

Wrong high Voltage Line

The high voltage line can also cause a thermostat failure. If there is a problem with the high-voltage wire, the thermostat will not be able to signal the HVAC system properly. A high-voltage wire damaged, loose, or disconnected causes thermostat problems.

Quality of the Thermostat

A lousy-quality thermostat is likely to fail after some time. Just like all mechanical devices, a faulty thermostat is a fluke that sometimes happens. A bad thermostat can create various problems, including not turning on the cooling or heating functions, not reaching the desired temperature, showing an error message, or displaying incorrect temperature readings.

Replace the Thermostat

You may need to change small components of thermostats, but in the worst-case scenario, when the thermostat is irreparable, you can need to replace the whole kit. This method is long-term but expensive.


Any homeowner does not desire a broken aircon thermostat. It is fixed with the help of some basic plumbing knowledge. You need to learn about the causes and the methods of improving a broken thermostat.

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