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

If your AC is blowing hot air, the first thing you’ll want to do is ensure that the issue is not something you can fix by yourself. Start by:

  1. Making sure your thermostat settings are on COOL not HEAT
  2. Making sure your fan settings are on AUTO instead of ON

If your AC is still blowing warm air after you’ve checked your thermostat settings, you most likely have a problem that requires professional assistance, such as:

  • Low refrigerant levels
  • Dirty evaporator coils
  • Dirty outdoor unit
  • Tripped circuit breaker

Below, we’ll explain these problems in greater detail so you’ll have a better understanding of why your AC might be blowing hot air and how an HVAC technician can fix the problem for you.

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Problem #1: Low refrigerant levels

Your AC actually cools your home by removing heat from the air with a super cold substance called refrigerant. The refrigerant circulates in your indoor unit and absorbs heat from the air. Then it moves to your outdoor unit via refrigerant lines where the heat is dumped outside.

However, if your refrigerant levels are low, your AC can’t remove as much heat from the air per cycle, which means the air may feel slightly warmer than it should.

If your refrigerant levels are low, in addition to your AC blowing warmer air, you may notice:

  • Ice forming on your indoor and outdoor units
  • AC blowing warm air in the daytime but cold air at night
  • Hissing or bubbling noises near the AC

Refrigerant lines work in a closed-loop system, so if your AC is low on refrigerant, it means you have a leak.

To fix a refrigerant leak, you’ll need to contact a technician. Refrigerant is a toxic substance, so you’ll need a trained professional to repair the leak and refill your refrigerant.

Reason #2: Dirty evaporator coil

When warm air blows over the evaporator coil, refrigerant absorbs the heat.

But if the coil is covered in grime, refrigerant can’t effectively absorb the heat from your home’s air, meaning that your AC will blow warm air back into your home.

A dirty evaporator coil can be caused by a clogged AC filter that needs to be replaced. While the filter’s job is to catch dust and debris before they enter your AC system, they don’t catch everything. If the AC filter isn’t changed regularly, the clogged filter can increase the amount of dust settling on your evaporator coil.

To prevent a dirty evaporator coil in the future, replace your AC filter every other month. However, if you think your evaporator coil is already covered in dust, you’ll want to contact a professional to clean it for you. The evaporator coil is typically located in hard-to-access places and can be difficult to reach.

Reason #3: Dirty outdoor unit

A dirty outdoor unit

As we mentioned above, to properly cool your home, your AC needs to remove heat from the air inside your home and dump it outside.

If your outdoor unit is covered in dirt or grass, your AC won’t be able to effectively dump the heat outside, which means warm air will blow through your home.

To clean your outdoor unit without risking damage to vital parts, you’ll want to hire a technician.

Reason #4: Tripped circuit breaker

Circuit breaker for the AC

ACs have two circuit breakers, one per unit. If the outdoor unit’s circuit breaker is tripped (i.e. in neutral position), the indoor unit will continue to blow air into your home—but that air will be warm.

You’ll want to check your circuit breaker box to see if the outdoor unit’s breaker tripped. The electrical panel should be labeled as “HVAC” or “AC.” If the panel is not labeled, look for a tripped switch. If the breaker is tripped, reset it by:

  1. Turning the breaker OFF (to the right)
  2. Turning the breaker ON (to the left)
  3. Waiting 30 seconds for it to reset

If the breaker trips again or a fuse blows, call an AC professional right away because there could be deep-seated wiring issues in your home. Do not reset your circuit again, you’ll overload the current and can cause serious electrical wiring problems.

Need help with an AC that is blowing warm air? Contact Climate Design

Beyond the issues we’ve listed above, there are other reasons why your AC is blowing hot air, such as:

  • Compressor issues
  • Capacitor problems
  • Leaky ducts

For an accurate diagnosis of the issue, reach out to our team. We have almost half a century of experience repairing ACs for Florida homeowners. Our technicians are knowledgeable about all brands and models so we’ll get your AC blowing cold air again.