My Air Conditioner Won’t Turn On, What Should I Do?

September 24, 2020

If you’re trying to cool your home but notice that your AC isn’t turning on, don’t panic. There are multiple issues that could be causing your AC to stay off, and some are very simple fixes.

The most common reasons your AC won’t turn on include:

  • Your AC is on the wrong thermostat setting
  • You have a dirty air filter
  • The circuit breaker has tripped
  • The condensate line is clogged

Below, we’ll look at each of these issues in more detail so you can get a better idea of why your AC won't turn on, and what you can do to fix it.

Rather enlist the help of a pro? We can help! Check out the AC repair services we offer or schedule a repair!

Issue #1: Wrong thermostat setting

Check Thermostat For Heat Pump Not Blowing

If your AC won’t turn on, it could simply be on the wrong settings. To turn on, your AC needs to be set to “COOL.”

If your AC is on HEAT or OFF, it won’t turn on, which could be your issue.

It's easy to accidentally bump or adjust your thermostat, changing the settings from cool to OFF or HEAT.

Our suggestion would be to double-check that your thermostat is set to COOL. If it’s not, change the setting back to COOL.

If your thermostat was already set to COOL (or you changed it to COOL and it’s still not turning on), there’s likely another issue with your AC system, so keep reading.

Issue #2: Frozen evaporator coil

Frozen Evaporator Coil

Another reason your AC may not be turning on is because of a frozen evaporator coil.

The evaporator coil is a very cold part of your indoor AC unit, and it can freeze if it doesn't have enough heat passing over it.

If your evaporator coil does freeze, the ice will eventually start to melt, and while your AC system is equipped to collect some moisture (from humidity in the air), it’s not equipped to handle that much liquid.

The bottom line is that your indoor AC unit can start to flood. Your AC system has a security measure in place, called a float switch, that will shut your AC off completely to prevent damage.

Your evaporator coil can freeze for a few reasons, but one of the most common reasons is because of a dirty air filter.

Your air filter is meant to collect dust and debris before it makes its way into your AC system. But, over time, your air filter will become so bogged down by dust and debris that it prevents air from entering your system. And, if the evaporator coil doesn’t have enough warm air blowing over it, it can freeze.

Dirty Vs Clean Fiberglass Air Filter2

To “fix” a frozen evaporator coil caused by a dirty air filter, simply turn your AC off for a few hours and replace your air filter (you may notice some water pooling near the base of your AC as the moisture on the evaporator coil melts). Then, turn your AC back on. If your AC starts working correctly, this was likely your issue.

However, if your AC system still doesn’t turn on, you could be dealing with a more serious issue like dirt buildup on the evaporator coil or low refrigerant levels. For each of these issues, you’ll need a professional’s help.

Issue #3: The circuit breaker has tripped

Circuit breaker tripped

Sometimes, the reason your AC won't turn on is simply because the circuit breaker has tripped.

To check this, take a look at your electrical panel. If the circuit breaker labeled “AC” has moved to the neutral position (not ON or OFF), turn your AC circuit breaker to OFF for 30 seconds. Then turn it back to ON.

If your AC doesn't start up, or does start up but shuts off again a few minutes later, don't attempt to reset your circuit breaker again. There could be a more serious electrical problem that an electrician will need to assess and fix.

Issue #4: Clogged condensate line

As we mentioned above, your AC is designed to collect some moisture from your home’s air. This moisture collects below the evaporator coil in something called a drain pan.

The moisture that settles in the drain pan then exits your home via the condensate drain line.

Evaporator Dehumidification Process Healthy

However, if there is a clog somewhere in the line, moisture can start to back up until it overflows the drain pan.

Evaporator Coil Drain Pan

As we also mentioned above, your AC system has a security measure in place to prevent your AC unit from flooding. If your float switch senses that the drain pan content is too high, it will trigger your AC to shut off.

You can fix this issue by trying to unclog your condensate drain line yourself. Here’s how:

Step 1: Turn your AC off.

Step 2: Locate the end of your drain line. This line is usually a white PVC pipe that's near your outdoor AC unit.

Condensate Drain Pipe

Step 3: Attach the end of a shop-vac to the end of the condensate drain line.

Step 4: Turn the shop-vac on for 1-3 minutes. Check the shop-vac to see if you were able to remove any debris.

Step 5: Turn your AC unit back on and see if this has solved the problem.

If your AC is still refusing to turn on, it’s time to reach out to an HVAC pro. There could be a tough clog or an issue with your indoor AC system that a tech will need to fix.

Having issues with your AC system? Let a professional step in

If you've tried the above fixes and your AC still won't turn back on, it's time to enlist the help of a professional. At Red Cap, we have years of experience helping Florida homeowners with their AC systems, so no matter what's going on with your AC, we can properly diagnose the issue and fix it.


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