“Why is my AC not blowing cold air?” I don’t think anyone could ask that question in a non-ticked-off tone, considering Florida’s ‘wonderful’ summer weather and all.

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Anyway, down to brass tacks.

In the year-round heat of Florida, having your AC not blowing cold air can be a real nuisance. The only worse thing than your AC unit not blowing cold air is when hot air is blown out of the vents instead. 

Air conditioner not blowing cold air but running? This could be caused by a variety of problems.

Here’s an overview of a few common issues found when you have air conditioning running but not blowing cold air:

  • The thermostat is on the wrong fan setting
  • Refrigerant leak
  • Dirty air filter
  • Dirty outside AC unit
  • Tripped breaker

Let’s go into each of these in more detail.

1) The thermostat is on the wrong fan setting

One of the most common reasons for an AC not blowing cold air is user error. If you find have an air conditioner not blowing cold air but running, chances are something was incorrectly set up.

Check your thermostat’s fan setting controls (you guessed it) the fan in the air handler, which is your AC’s inside unit.

Check the fan setting now.  What is it set on??

If it’s set to ‘On’ you may have found the problem. ‘On’ means the fan runs 24/7 even when the air isn’t being cooled. That’s why the air may feel warm or hot sometimes and you may find your AC not cooling.


Turn your fan setting to ‘Auto,’ making the fan automatically turn on only when you need cooling.

2) Refrigerant leak

Another potential reason to your air conditioner not cooling but running could be a refrigerant leak.

Refrigerant is a heat transfer liquid; it’s responsible for absorbing the heat from your air. So if you’re low on refrigerant, your AC can’t cool your air well, especially on hot days.

The only way refrigerant gets low is if you have a leak (refrigerant isn’t used up like gas).

Signs you have a refrigerant leak:

A refrigerant leak can be identified on your outside unit. Even in Florida, it might have frozen due to some AC condensation.

  • Frozen refrigerant line.
  • AC blows hot air during the day, but cold air at night
  • You hear a hissing or bubbling noise near AC (this means the leak is significant)


If you see these signs, you need to schedule an air conditioner repair. The technician will need to find the leak, repair it (if possible), and add refrigerant.

Luckily, this is not an expensive fix!

3) Dirty air filter

When you leave your air filter in your AC system too long, it gets full of dirt (especially during the monsoon season) and becomes worse than useless’it can do real damage to your AC.

A dirty air filter blocks return airflow to your air conditioner, preventing your AC from cooling normally.


Check the filter at least once a month and change your air filter ASAP if it’s dirty.

4) Dirty outside AC unit

Long story short: The outside unit’s job is to disperse heat from the refrigerant so it can absorb more heat from your air.

Anyway, if the outside unit gets too dirty, it has trouble dispersing the heat, and thus your AC struggles to cool your air.

Learn more in our article Dirty AC Condenser Coils: Why You Need Them Cleaned in Phoenix.

Solution 1

Clean the outside unit at LEAST once a year using a garden hose on a gentle setting.
DON’T go full blast or you’ll bend the condenser coil fins and hinder airflow.

Solution 2

If you want to get your outside unit properly cleaned (and prevent AC breakdowns,)
then you need air conditioner maintenance.

It’s just like getting maintenance for your car (except instead of every 3,000-6,000 miles, it’s once a year).

5) Tripped breaker

Your air conditioning unit has two breakers: one for the outside unit, another for the inside.

If the outside unit’s breaker trips, then the inside unit will continue to blow air in your home, it just won’t be cooled off.


Check your breaker box and see if the inside unit’s breaker is tripped if so, reset the circuit breaker. If the breaker trips again, DON’T reset it. Doing so could damage your AC.

Learn why in our article ‘Why is My Air Conditioner Tripping the Circuit Breaker?

You’ll need to schedule an air conditioner repair to solve this problem.

Just a few problems of many

The above 5 issues are just a handful of problems that could have your home AC not blowing cold air. Luckily, having your AC not cooling doesn’t have to be the end of the world when you can count on Performance AC technicians in Tampa.

To find the true problem, call a professional A/C technician to check your system.