Common Reasons Why Your AC Unit May Not Be Working

Posted on: 6 April 2015


An air conditioner biting the dust can be the worst part of summer. It's especially true when you call a technician and they're all booked up for days. The uncomfortable heat may encourage you to try to fix your air conditioner on your own. The first thing you need to do is diagnose the problem. You can start by learning the most common air conditioner problems. Some you can remedy yourself, while others will require a professional.

Your Air Conditioner Isn't Turning On

If you air conditioner won't turn on at all, there are a couple common reasons why this may be happening. Many times, it is either a problem with your thermostat or an electrical issue.


Your thermostat may have a built-in timer that delays the activation of your heating and cooling equipment. First, make sure the thermostat is indeed set on cool. Give it some time to complete its last cycle in case there is a timer. Turn it off of auto and onto on if your thermostat has those options. It will bypass the timer and kick it on automatically. If that doesn't work, your thermostat may need to be calibrated by a professional.


You air conditioning unit may not be receiving power. Fine the main fuse panel in your house and check that there isn't a tripped circuit. If it's in the "on" position, you can try clicking it off and then on again to see if it helps. If your AC unit has a breaker panel on the outside of the unit itself, unplug your AC and check the panel. If there are any blown fuses, you have likely found your problem. Replace the fuses and plug it back in. If you can't find the source of the issue, wait for a technician. You don't want to mess around with electrical problems if you don't know what you're doing.

Your Air Conditioner Blows Warm Air

If your unit is turning on, but it's blowing warm air instead of cold air, there are two likely reasons for this. Your air filters may be too dirty or your unit may need the refrigerant refreshed.

Air filters

Air filters are essential for filtering out dust while blowing air through the ducts into your home. You need to change your air filters every month to keep your air clean. In addition to clean air, it extends the life of your furnace and air conditioning unit. When the dust and debris build up on you filter, your equipment has to work a lot harder to blow air through your home. If there is an extreme amount of build up, the cold air may be warming up while trying to push through the filter.


While many units can run properly for years without being recharged, other need some Freon or Puron added on a regular basis. If your air conditioner is blowing warm air and changing the air filter didn't help, this is likely the case. Adding Freon or Puron yourself is not an option. Refrigerant is not sold to unlicensed individuals.

Your Air Conditioner Is Noisy

If your air conditioner is making unusual noises, this can also be from two common issues. It could be an installation issue or a belt.

Improper installation

If you have a new air conditioner and it's making a loud rattling or vibrating noise, it may have been installed incorrectly. Turn off your air conditioner and call your technician immediately,


If you have an older air conditioner, you may be having a problem with the air handler. In older AC unit models, the air handler is driven by a belt. The belt connects the blower and the motor together. If the belt slipped, it may be making a terrible squealing sound. Turn off your air conditioner immediately and don't turn it on until it has been looked at by a technician.

Air conditioners are powerful machines. They need proper maintenance and repairs to last. While you can check your own fuses and air filters, you need to call an air conditioning repair technician if your problems go beyond simple fixes.