Why Does My Heater Work But Not My AC? [Possible Reasons And Fix]

Bathrooms & Utility Rooms, Blog, Electrical & HVAC

During summer, the air conditioner is one of the most used appliances in the home. However, it can get pretty frustrating not having your AC work, but the heater works perfectly fine. You wonder, “why does my heater work but not my AC?”

There are several possible reasons for this. Some include damaged components, dead thermostat batteries, blown fuse, bad capacitors, etc. Don’t worry, you don’t have to suffer in this hot weather.

This article highlights all the possible reasons why your heater works but your AC doesn’t and what to do. I will also answer other questions you might have. So, keep reading to learn more.

Why does my heater work but not my AC?

In this section, I will highlight some of the most common reasons why your heater works but not your AC.

1. Dead thermostat batteries

Most of the time, the issue is not even with the air conditioner itself but rather the thermostat. Simply check if anything is displayed on the thermostat first for a start.

If nothing is displayed, then the batteries are possibly discharged. Changing the thermostat batteries should do the trick. You can also call an HVAC company to help out but it would probably cost more than just changing the batteries.

2. One of the disconnect switches is off

Building code requires disconnect switches to be installed both outdoors and indoors next to the AC unit. It could have been turned off by accident. So ensure you check the indoor and outdoor disconnect switch first. 

3. You have a tripped circuit breaker

It could also be that the circuit is overloaded, causing it to trip. Simply reset it and try again. If this happens again, try shutting off other equipment to see how things go. If it continues, contact a professional to help diagnose the problem.

4. You have a blown fuse

It could also be an issue of a blown fuse between the thermostat and the AC unit itself. I recommend contacting a professional to fix this for you except you are specifically trained to handle issues like these. Once the fuse is changed, the AC unit should work just fine.

5. It’s a case of a blown transformer

When the wiring is short-circuited, it causes the transformer to have issues. One of the most common issues is a blown transformer, causing the AC to stop working entirely. The best solution is to have a professional change the transformer and the wiring so it doesn’t happen again.

6. Faulty capacitor

An air conditioner unit has either two single capacitors or one dual capacitor. An AC unit that has two single capacitors requires one to start the AC and the other to facilitate its operation. 

It could be that either the dual capacitor is faulty or one of the two single capacitors is bad. They don’t naturally last forever, they have to be changed at some point. It’s best to have a professional do this for you.

7. You have a dirty AC coil

It is also possible for the air conditioner to be working but produces only warm air. This usually happens when the AC coil is dirty. The AC coil is supposed to be cleaned from time to time (at least twice a year). Neglecting to clean the AC coil might affect the efficiency of the air conditioner. You can clean the AC coil yourself with common household detergent and water. You can also have a handyman clean the AC coil for you.

8. One of the air conditioner components is damaged

Many instances can lead to any of the air conditioner components being damaged. It could be that someone accidentally pulled a plug, something heavy fell on the outdoor unit, etc. Avoid trying to fix this yourself, it is best to have a professional do the repairs personally.

What should you do if your heater works but not your AC?

A few of these issues highlighted above usually require simple DIY solutions. However, some of these issues are more complex or dangerous so it’s best to seek the expertise of an authorized professional. That said, if the AC unit has been piling up bills lately, it would be best to look into getting a new AC.


Why is your AC not turning on?

The thermostat is one of the main reasons behind the AC unit not switching on. Common issues are; power surges and low batteries.

Why is heat coming out instead of AC?

This usually happens when there are electrical issues within your central AC unit. Common reasons include short wiring, faulty electronics in the furnace, and electrical problems with the thermostat.

In summary

No one likes a faulty air conditioner or heater, but it’s particularly confusing when the heater works just fine while the AC is not working. Some common reasons include a faulty capacitor, blown fuse, damaged AC components, and so on.

While most of these issues can be addressed easily as mentioned in the article, some require expertise. So, most times, contacting a technician is the best way to fix your AC.

I hope you found this article helpful, also see if you can plug the air conditioner into the power strip or surge protector.

Thanks for reading.

Leave a Comment

About Samkins

Samkins Construction Inc specializes in custom home building, general contracting, design-build, architectural design, construction management, and real estate services.


Sign up to receive the latest news and updates from our company.

More questions? Get in touch