Why Is My Air Conditioner Blowing Hot Air? A Florida Tech Explains

August 07, 2015

Warm or hot air coming from the vents of your AC?

Yep, that’s a problem.

The truth is, feeling hot air from your home’s AC could be caused by a ton of different problems. Here are a few of the most common.

Wrong thermostat setting

Double check your thermostat settings. Make sure it isn’t switched over to HEAT (oops!) and your fan isn't in the ON setting. ON allows your system’s fan to continue to blow air through the vents even when your AC is cycled OFF and not cooling that air. 

These settings can get switched by an accidental bump or nudge easier than you’d think.

Solution: Switch your thermostat back to COOL and your fan setting to AUTO. (AUTO means the fan will automatically turn on only when your home needs cooling.)

Dirty outside (condenser) unit

The outside unit’s job is to disperse heat from the refrigerant so it can absorb more heat from your air. If the outside is caked in dirt or visibly clogged by tall grass or bushes, your AC will struggle to cool your home’s air.

Solution: Get your AC coils cleaned. You can clean them yourself with a coil cleaner or have a trusted tech do the entire thing for you as part of a preventative maintenance plan.

Dirty evaporator coil caused by a dirty air filter

The evaporator coil carries cold liquid refrigerant that helps absorb heat from your home’s air. If it’s clogged with dirt, the air being blown over the coil cannot be cooled off, resulting in unconditioned (warm) air being recycled back into your home.

Solution: A dirty evaporator coil (inside cooling coil) is usually caused by a dirty air filter or by running your AC without a filter. You can change the filter, but you’ll need a professional to properly clean your evaporator coil.

Tripped circuit

Most AC’s have two breakers: one for the outside unit, another for the inside. If the outside unit’s breaker is tripped, then the inside unit will continue to blow air into your home–the air just won't be cooled.

Solution: Check your breaker box and see if the outdoor unit’s breaker is tripped. If so, switch it back on. If it trips again, DO NOT reset it. Multiple overcurrents can lead to major AC damage and serious electrical issues that could cause a fire.

Contact a professional to help you fix this problem.

Low refrigerant

Refrigerant is a gas that transfers heat from inside your home to the outside. If you’re low on refrigerant, your AC can’t absorb heat from your air. This can lead to your AC blowing warm air.

Solution: Refrigerant isn't used up like gas in a car. Have a professional air conditioning contractor find the leak, drain out the remaining refrigerant, repair it then add the right amount to your system.

Need a professional to take a look?

Advanced Air serves Southwest Florida—including Fort Myers, Naples, Cape Coral, Bonita Springs, Estero, Port Charlotte and more. Give us a call or contact us online for help find and fix the problem with your air conditioner.