It may take a little while before you even notice your AC unit outside isn’t working.

Has this ever happened to you? You lower the temperature as usual, you hear the inside fan motor running, and keep doing what you were doing. After a while you realize it’s not getting cooler in your house … in fact, it’s getting warmer! You walk back to your thermostat, and it’s gone up a degree or two, but it says the AC is on. You walk outside to look at the condenser (outdoor AC unit) and find it’s not running. Ugh!

Here are 10 reasons why your AC won’t turn on:

10. Bad Condenser Fan Motor 

The condenser fan motor expels the heat removed from your home outside. It does this by removing heat from the refrigerant flowing through the outdoor coil. It also assists in keeping the compressor cool. Without being able to remove heat, the compressor will overheat and prevent the condenser unit from running.

9.   Faulty Capacitor 

capacitor aka voltage absorber aids the connected component in running and not overamping. Both your condenser fan motor and/or compressor may require a capacitor. Some new compressors do not require a capacitor due to the inverter technology they use. If your capacitor fails or is faulty, it’s likely your AC unit won’t turn on. It’s also not uncommon for a faulty capacitor to cause it’s connected component damage as well.

8.   Bad or Damaged Compressor 

The compressor is to the AC unit what the heart is to the body. A bad or faulty compressor is never good news. So, if you’re technician tells you it’s a bad capacitor or fan motor, count your blessings, you just saved money!

7.   Broken PCB (Printed Circuit Board) 

Most modern AC units utilize electronic circuit boards that control the mechanical components. Every year, these boards get bigger and more complex and unfortunately – are usually unrepairable. In the old days, we could often take these boards back to our shops and repair them. However, today we live in a “disposable” world. Even a small problem on a PCB can be the reason your AC unit won’t turn on.

6.   Low Refrigerant 

The compressor is to the AC what the heart is to the body, the refrigerant is the blood. If your system runs low on refrigerant, the low-pressure switch is the reason your AC unit won’t turn on. The low-pressure switch is designed to protect the compressor from running without refrigerant flowing.

Pro-Tip: Your air conditioning system is a “sealed system” which should never lose refrigerant. If your AC unit won’t turn on because of low refrigerant, it means you have a refrigerant leak. Much like a cars oil leak, your technician will need to find the leak, repair it, and then add refrigerant. If not, you will continually be repairing the system and buying more refrigerant. The worse the leak, the more often you’ll need more refrigerant.

We talked about the outside air conditioner not turning on, let’s turn our attention to the inside unit now. Most of us have what’s known as a split air conditioner or split heat pump. A split air conditioner has an outdoor AC unit connected via pipes to an indoor coil & furnace. A split heat pump has an outdoor heat pump which provides both heating and cooling. That unit is connected to an indoor air handler with a coil inside it.

There are fewer components in the indoor unit than the condenser. That said, there are a few that if broken, would explain why your inside AC unit won’t turn on.

5.   Bad Indoor Fan Motor 

This motor circulates conditioned air through the return, across the evaporative coil, and into the ductwork. If your indoor AC unit won’t turn on and you don’t feel air movement, the indoor fan may be faulty.

4.   Faulty Capacitor 

Many (not all) blower motors also utilize a capacitor the same way the outdoor fan and compressor do. A failed or weak capacitor could cause your AC indoor unit to not run.

3.   Dirty Coils / Filters 

Dirty evaporator coils and/or plugged air filters will restrict airflow across the coil. If left unchecked season after season, this dirt will restrict air to the point the coil freezes over. Lack of maintenance, pet hair, dust, and dander buildup can all lead to plugged coils and further damage equipment components.

2.   Circuit Board Failure 

Again, just as your outdoor unit uses PCBs, so do many indoor units. Circuit board failures are not uncommon as they often must combat their two biggest “killers,” heat and dust.

1.   Refrigerant Leaks 

both indoor and outdoor coils can develop refrigerant leaks. Remember, the indoor and outdoor coils are connected via refrigerant lines (which themselves have the potential to develop a leak). No matter where the leak is located, inside or outside, low refrigerant can explain the reason your AC won’t turn on.

At the end of the day, just choose the right air conditioning contractor!

For expert air conditioner service & replacements give us a call. Rostron Premium Home Services, located at 2490 Tiltons Corner Road in Wall Township! 732-223-8221.