AC Not Working But Heater Is—What’s Wrong?

Heating and cooling are both essential to keep your home comfortable. It will be a nuisance if the weather starts to get warm and your AC is having a problem. What causes the AC to suddenly stop working when the heater is just fine? Don't worry, we have scoured the net to provide you with the best answer. 

An air conditioning unit may not work even if the heater does. It could be due to any of the following issues:

  1. Dead thermostat batteries
  2. Indoor/outdoor disconnect switch 
  3. Tripped circuit breaker
  4. An issue with the fuse
  5. Transformer concern
  6. Capacitor failure
  7. Dirty coils and filter
  8. Damaged HVAC components 

Keep reading as we elaborate on what's wrong with your air conditioning unit. We'll also discuss related topics about AC not getting cold enough, AC leaks, and your AC fan not working.

Air conditioner unit outdoors in side yard of a brick home in hot summer season. No people - AC Not Working But Heater Is—What's Wrong

Reasons Why Your AC is Not Working But the Heater Is

HVAC heating and air conditioning residential units or heat pumps

An air conditioner can be repaired when it stops working all of a sudden, although preventing it from happening is better than dealing with the heat inside your home. Make sure that your AC is in good condition so that it will not need to be repaired when you need it the most. Find out the reasons why your AC is not working. 

1. Discharged Thermostat Batteries

If your AC is not working, it may be due to dead thermostat batteries and not the unit itself. Check for the display on the thermostat. If it doesn't show anything, it might mean that only the batteries need to get charged. 

2. Indoor/Outdoor Disconnect Switch 

Always check if the indoor or outdoor disconnect switch is on. If it's off, your AC will stop working on cooling your space. Even if you're sure that you left it on before, accidents can happen sometimes. Somebody may have bumped into it and accidentally turned it off. Just turn it back on for your AC to work again. 

3. Circuit Breaker Trip

Rooftop HVAC installation, with electrical panels, breaker, pumps, and water pipes.

When your AC  stops working, you should also check the breaker. It may be disconnected and needs to be connected to the HVAC system. When the circuit has overloaded, the circuit breaker will trip. It will cause the AC unit to shut down to prevent it from bursting. But if the circuit breaker keeps on tripping, it's time to call for professional service. 

4. Busted Fuse

When the fuse is busted, the AC unit will stop working. It has to be replaced to make the AC up and running again. This may happen especially if the fuse has not been replaced for a long time. If you are trained to fix this issue, you can do it, but it's best to call a technician to have it fixed.

5. Transformer Concern

If the transformer is having an issue, it can cause the AC to stop working. It can happen when the wiring is short-circuited, causing it to blow. The best thing to do is to replace the transformer to make the AC work. Change the wirings as well to prevent it from happening again in the future. 

6. Failed Capacitor

AC has requirements to work properly. It needs to have 2 capacitors to be efficient. One is to start the AC and the other is to keep on running. These giant-looking batteries hold power and keep the AC on. However, they don't last forever and need to be replaced someday.

When the capacitors fail, they must be replaced. It must be done by an HVAC professional to ensure that the AC will work again.

7. Dirty Coils and Filter

Someone holding a very dirty clogged air conditioner furnace filte

If the AC is working but only produces warm air, it may be due to dirty coils. This happens when the HVAC system is not serviced regularly. The dirt on the coils accumulates over time. It can't cool your home as efficiently as before. The heater may still work, but the AC will not. It can only provide warm air and will no longer have a cooling effect.

The filter needs to be changed regularly to keep the AC unit running smoothly. It accumulates dust and dirt over time. If you don't clean it, the filters will be clogged. That will affect the airflow on your air conditioning unit. It can freeze parts of the AC and can't diffuse cold air anymore if there's no proper airflow.

8. Damaged HVAC Components 

Various instances can cause damage to the HVAC system like accidentally pulling a wire or if there's a busted line. Also, the AC will no longer work if a heavy object falls on the outdoor unit. The best thing to do is to have a regular HVAC service to maintain the system.

Simple troubleshooting might make the AC work and start cooling your home again. However, if it's a damaged HVAC or an electrical issue, avoid trying to fix it yourself. It's best to call an AC technician instead to fix your air conditioning unit safely. 

Why the AC is Not Cold Enough?

Air conditioner unit outdoors in side yard of a brick home in hot summer season. No people.

When the air on the AC is not cold enough, check the vents and make sure they are open. It will be harder to make the entire house cold if one vent is closed. If there's a leak on the refrigerant line, it can also affect the cooling level of the AC unit.

If you have an old AC unit, it may no longer be efficient due to wear and tear. The wrong size or improperly installed AC units can also cause a problem. If it's too big for the area, it will cycle too quickly and reduce its efficiency. But if the unit is too small, it will break down faster since it will have a hard time making a huge area cold. 

What to Do When The Water Leaks From the AC

If you notice that the AC is leaking water from the indoor unit, turn it off immediately. That way, it will prevent water damage to the unit. Water leaks happen if the drain line is clogged. Try using a vacuum to unclog the dirt. Check for rust on the drain pan as well. If the pump has broken down, call a technician to replace the parts.

When it's hot and humid outside, it's normal to see water leaking from the AC. As long as it happens while it's in use, you have nothing to worry about. When the ice melts from the unit, it will cause water to leak. But if the water leak is caused by other reasons, clean, and replace the filter instead.

Why is the AC Not Turning On or Off Automatically?

If the AC unit isn't turning on, adjust the thermostat. It's the common fix for this issue but if it doesn't work, you need to call a technician. They should know if it needs to be repaired or replaced. 

The AC unit may not turn off if the filter is dirty. Cleaning or replacing it will be the best solution. Old or small AC units need to work harder so they're not turning off as they should. Replace them with a new model and the correct size to avoid this issue.

Why Is the AC Fan Not Working?

Air conditioner during the summer heat. It is the savior of many as a way to get out of the heat and relax

When the AC fan is not working inside, you need to check the breaker. If it's not tripped, move on to the air filter. It may be blocked but you can fix it without calling a technician. Check for ice on the coil and refrigerant lines as well. If it's present, let it melt and try the fan again. If it still doesn't work, it's a frozen coil. Call a technician to fix it for you. 

Check if the outdoor unit of the AC is not cooling your home. The outdoor fan must be spinning. If not, check for the fuse box or breaker. Reset it to correct the issue. If it doesn't work, check if the capacitor is working. Push the fan using a stick to see if it will spin. If not, call a technician to fix this issue and turn off the unit until service arrives. 

For more information, check out this article: Air Conditioner Fan Running Too Slow—What Could Be Wrong?

In Closing

There are several reasons why your AC is not working even if the heater works. The extent of the problem will let you figure out whether or not you need to call for a professional HVAC service.

Sometimes troubleshooting may not work. Most of the time, calling a technician is the best way to fix your AC. It will let you enjoy the cool temperature inside your home on a hot day again.

Before you go, you may want to look into these other posts:

 Rheem AC Not Cooling – What Could Be Wrong?

 Window Air Conditioner Blows Cold Then Warm – What’s Wrong?

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