AC Thermostat Not Working [Solved]

Share This Guide

Is your ac thermostat not working? You are in the right place. We have put together issues that can prevent your air conditioner from working properly, these include

  1. Broken sensors
  2. Low batteries in a thermostat
  3. An open furnace door
  4. Bad thermostat wiring
  5. Tripped circuit breakers
  6. Unit it locked
  7. Not properly located
  8. A thermostat the needs replacement
ac thermostat not working
Honeywell Ac thermostat

Also read: Honeywell Thermostat Heat Not Working

7 Reasons For Your Ac Thermostat Not Working

1)Broken Sensors

When your ac thermostat stops working, it could be a result of broken or damaged sensors. Thermostats have different sensors that work together to give you the temperature you need.

However, when sensors malfunction or get broken, they will not work according to the way you want them to. You may experience either too cold temperatures or too warm, totally different from what you set on your thermostat.

Thermostat sensors can be best checked by a HVAC professional. If you are using a mini split air conditioner with a remote control, you can check on your sensors. They are usually found near the evaporator coil of your indoor unit.

You can try fixing your sensor by first turning off your AC unit and accessing the evaporator coil. Check if the sensor is bent and if it is carefully put it back in position

 In other cases, sensors can’t easily be fixed that is why, your HVAC technician will probably advise you to replace the whole thermostat.

2) Low Battery

Dead or bad batteries could also prevent your ac thermostat from working. In many cases, homeowners that have issues with their thermostats, the problem turns out to be simply low batteries.

There are many thermostat models that will warn you when the battery is low. But others do not. Low batteries can prevent your thermostat from turning on your air conditioner. And they can also prevent your thermostat from turning off your AC unit.

Usually, when your thermostat batteries are low, your may have faint display. Sometimes the display will go and come back. If you think you have low batteries, you can easily replace them yourself.

Remove your thermostat from the wall and see what type of batteries it takes. A typical AC thermostat will work with a pair of regular AA batteries.

PS: When replacing batteries, ensure that you replace both batteries with a new pair.

3) An Open Furnace Cover

Other times, when your thermostat is not working, its probably because your furnace cover it open.  If your thermostat has a blank screen, then it’s a good sign that your furnace door is not securely closed. You should ensure that your furnace door is tightly closed.

Some HVAC systems have door switches. These switches will cut power supply to your HVAC system when the door is not closed properly.

4) Bad Thermostat Wiring

An AC thermostat will not work the way it should with bad wiring or has some loose wires hooked up to it.

It is worth noting that each functionality of your thermostat has a separate terminal where different wires from your HVAC system are connected. If some wires are not connected or are just loose, they could cause your thermostat to misbehave, or not work at all

Other times when rodents find their way places such as the attic, they could bite the cables and negatively affect how your thermostat works.

You can check if your thermostat wiring is fine by removing your thermostat from the wall and opening it. If you are not sure about the wiring designation for your system, you can find this information on the inside of the circuit control board compartment.

Otherwise, if you feel fixing the wiring your thermostat too much of a hassle, it’s in order to call HVAC professionals.

4) Tripped Circuit Breaker

A tripped breaker could be the reason your ac thermostat doesn’t have power. After checking with your furnace door and it’s securely closed, go into the electric box, and verify that there are no tripped breakers. If there are, flip them back and this should restore power to your thermostat.

5) Locked Thermostat

If your thermostat isn’t changing temperature at all, it could be locked. Some modern thermostats come with a ‘locking’ feature, that makes it possible for you to lock your thermostat to prevent others from making temperature adjustments.

Are you the only user of that thermostat?  If not, find out if anybody else in your house or office has locked it. By turning off the ‘locking’ feature, you should be able to make changes to your indoor temperature without any problems.

6) Thermostat Not Placed in A Good Location

A thermostat that is placed in a wrong location will have issues reading the temperature. For example, a thermostat that is placed near a stove, or one that is placed in a room whose vents and registers are closed.

Make sure that your thermostat is not placed in rooms with heating appliances. If there are vents or registers, ensure they are not closed of blocked.

Another place to avoid placing your thermostat is near the window.  When sunlight falls on your thermostat, it will read false temperature and eventually misbehave.

Read also: Honeywell Thermostat Blank Screen [7 Fixes]

7) A Thermostat That Needs Replacement

Finally, an ac thermostat that is too old may not work properly. Thermostats can stay for about 10 years on average before you’ll have to replace them. If it has been over 10 years since yours was installed, it’s perhaps the best time you think about getting a new one.

Before getting a new one just makes sure that it is compatible with your existing HVAC system. These days you can find many types of thermostats on the market including the programmable ones and the smart ones.

While programmable thermostats provide you with the convenience of scheduling temperatures at different time, smart thermostat allow you to adjust your home or office temperatures from wherever you are using your smart phone or laptop.

However, programmable thermostats are not as expensive as the smart thermostats.

Final Thought

What we have seen in this guide are the issues that are responsible for your ac thermostat not working properly. Hopefully, our tips have been helpful. If you are unable to solve the problem after going through our tips, perhaps call HVAC professionals.  They might be able to say exactly what is wrong with what. Thanks for reading.

Share This Guide

Leave a Comment

Don't Settle With A Broken AC

(National Database) Call 1-877-342-2087
To Find 24/7 AC/Heater Repair In Your Area