Honeywell Thermostat Not Turning On AC: Troubleshooting and Solutions

Summer’s sizzling heat is in full swing, but your Honeywell thermostat is stubbornly refusing to unleash a refreshing gust of cool air.

It’s like having a lifeguard who forgot how to swim when you’re desperately seeking relief from the scorching temperatures.

We understand the frustration of battling the heatwave without the cooling comforts of your AC. Our HVAC superheroes have assembled an arsenal of troubleshooting solutions to revive your AC and make it roar back to life.

From unraveling mysterious malfunctions to reigniting the chilling powers of your Honeywell thermostat, we’ve got you covered.

Why is my Honeywell thermostat not turning on my AC?

There are a few common reasons why your Honeywell thermostat may not turn on your AC.

  • One reason could be that the thermostat is not properly set to cool mode, which can easily happen if you use it in heating mode during winter.
  • A tripped circuit breaker or a blown fuse, which needs to be checked by an electrician.
  • A malfunctioning compressor or fan motor. If these components are damaged, they will prevent the AC from turning on and cooling your home.
  • An issue with the wiring between the thermostat and air conditioner unit causing them not to communicate properly.

It’s important to note that sometimes issues with your Honeywell thermostat may not actually lie with the device itself but could stem from problems within other parts of your HVAC system.

It’s always best to troubleshoot before calling for professional help, as some issues can quickly be resolved without spending money on unnecessary repairs.

What are some troubleshooting solutions?

If you’re experiencing a situation where your Honeywell thermostat is not turning on your AC, there are some troubleshooting solutions that you can try before calling a professional.

  • Check if the power source to both the thermostat and AC unit is turned on. Make sure that the circuit breaker or fuse box hasn’t tripped. If it has, reset it and see if this solves the issue.
  • Ensure that the batteries in your thermostat are fully charged and working properly. Sometimes simply changing out old batteries for new ones can fix any communication problems between your thermostat and AC unit.
  • Inspect all wiring connections to ensure they’re tight and secure. Loose wires can prevent proper communication between devices which could lead to system malfunctioning.
  • Check if a dirty air filter is clogging airflow through your HVAC system, which might cause cooling or heating cycle issues. A simple change of air filters may just be what you need to get things back in order.

These basic troubleshooting steps may save you time and money by preventing a costly service call from a professional technician.

How can I fix this issue?

If your Honeywell thermostat is not turning on your AC, there are a few things you can do to troubleshoot and potentially fix the issue yourself.

  • Check to make sure that the thermostat is set correctly. Ensure it’s in cooling mode and the temperature is lower than the current room temperature.
  • Check if there are any tripped breakers or blown fuses. If so, reset them or replace them accordingly.
  • It would be best to inspect all wiring connections to ensure they are properly connected and secure. Loose connections may cause communication issues between your thermostat and AC unit.
  • If these solutions don’t work, try resetting your thermostat by removing it from its baseplate for 30 seconds before reattaching it. This will sometimes solve simple communication problems between the two devices.

Try these troubleshooting steps if your Honeywell thermostat doesn’t talk to your AC unit. If so, call an HVAC technician.

Should I call a professional?

If you have tried all the troubleshooting solutions and your Honeywell thermostat is still not turning on your AC, then it might be time to consider calling a professional. While DIY fixes can save you money in the short term, a wrong move could lead to more costly damages.

Before making any calls, make sure to check if your thermostat is still under warranty. If it is, contact Honeywell customer service for assistance with repairs or replacements.

Another reason you should call a professional is if you are unfamiliar with electrical wiring. Working with electricity can be dangerous and potentially fatal if done incorrectly. A certified HVAC technician has the necessary tools and knowledge to safely diagnose and fix any issues without risking harm.

Calling a professional ensures that the problem will be fixed correctly the first time around. In the long run, this saves you time and money as they have experience dealing with various AC units and thermostats.

While it may seem like an added expense at first glance, calling a professional could ultimately save you from bigger headaches down the road.


A Honeywell thermostat not turning on the AC can be a frustrating issue to deal with. However, it is often caused by simple issues that can be easily resolved through troubleshooting.

Following the steps outlined in this article, you should be able to identify and fix the problem.

If you have tried all of these solutions and your Honeywell thermostat still isn’t turning on your AC unit, it may be time to call a professional for assistance.

A qualified HVAC technician will have the experience and tools necessary to diagnose and repair any underlying issues that may be affecting your system.

Regular HVAC system maintenance can help prevent issues like this. You can prevent major problems by scheduling annual checkups with an experienced technician.

Your Honeywell thermostat should provide reliable performance for years with proper care and attention.


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