5 Most Common Air-Conditioning Problems and Repairs

Use the table below to start troubleshooting what may be preventing your HVAC system from cooling your house like it should:

#1 Most Common Air Conditioning Repair – Bad Capacitor

If your thermostat seems to be working properly, air is blowing from your vents but it’s just not cold, find your outside unit (condenser) and see if it’s working. There are 2 components the compressor and the fan motor. With a trained ear you can hear both. The fan of course makes a whirring noise, the compressor is like a deep buzz like a refrigerator running. Holding your hand above the fan should feel warmer than the outside air. If there is a buzzing or humming coming from the outside unit but nothing is turning or blowing there is a good chance your capacitor is bad.

Capacitors help the electric motors that are in your air-conditioning system start and run. Specifically they provide a boost of energy during the starting phase to get the motors up to speed. Over time capacitors weaken and eventually if they are not replaced they will “blow” which renders them useless and can sometimes cause other issues inside the unit. 

Average repair cost in the industry:  $150-$300 plus diagnostic charge

#2 Most Common Air Conditioning Repair – Low Refrigerant

The refrigerant in your air-conditioning system, most often R22 (Freon) or 410A (Puron), is what actually transfers heat to make your system cool. If the refrigerant is too low the system will struggle to keep up, it may freeze and will ultimately not cool your house efficiently (or at all).

Most low refrigerant is a case of a slow leak so the symptoms become more and more pronounced if you are paying attention. You may notice your air-conditioning running longer and longer and the temperature you have set, harder and harder to achieve.

Adding more refrigerant to bring your system back to cooling properly is not too difficult, the problem is there is a reason your system is low on refrigerant. It may be a slow leak but refrigerant is escaping somehow. Usually this occurs in the evaporator coil and if the leak is significant enough it may be advisable to either replace the entire system (if it’s old enough) or replace the evaporator coil. 

Average repair cost in the industry:  $150/pound for R22, $70/pound for 410 plus diagnostic charge

#3 Most Common Air Conditioning Repair – Clogged Condensate Drain Line

As your home is cooled it is also being dehumidified. The process of cooling the air actually causes moisture to be removed at the same time. That moisture has to be caught and drained properly outside your house. When installed a PVC drain line is run from your system to the outside and all is well. The problem is that over time algae and other things tend to restrict and clog the drain line until it no longer drains properly. When this happens it starts to back up inside the unit and eventually fills up a secondary drain pan instead of soaking through your ceiling or running onto the floor. These secondary drain pans contain a safety switch to cut off the unit when they fill up. In addition, the current code requires an “SS2” safety switch which is designed to cut off before any water even overflows into the safety pan.

When the safety switch is triggered several things can happen, depending on how it is wired. Most commonly the thermostat will go blank because the safety switch interrupts it’s power. Alternatively the blower and thermostat may remain non but the condensing unit will be turned off.

If you’re adventurous you can track down your air-handler/evaporator and check for proper drainage by looking for water in the pan or lifting the SS2 switch (see picture). If the unit comes on when you lift the SS2 switch or you see water in the pan, you’ve found your problem! You can attempt to clear the drain line yourself, but often compressed air or other methods are used by the pro’s to get things going.

Average repair cost in the industry:  $150 plus diagnostic charge

#4 Most Common Air Conditioning Repair – Failing Blower Motor

Your blower motor is responsible for moving air inside your home/ductwork. Blowers are pretty reliable but they still rank in the top 5 for repairs. They are often in either hot or humid areas and don’t get the love and attention they deserve sometimes, including lubricating their bearings or keeping them free from dirt and debris. In addition, older motors have capacitors to help them start and as those capacitors age or wear out additional stress is placed on the motor during startup.

If you smell electrical burning in your ductwork or hear a rotating banging or grinding sound it is most likely coming from the blower. There’s not much you can do to fix it yourself but you should turn off your system to prevent any further damage or possible fire. 

Average repair cost in the industry:  $800-900 plus diagnostic charge

#5 Most Common Air Conditioning Repair – Bad Condenser Fan Motor or Compressor

Maybe we are cheating by lumping these together, but together they definitely qualify as a top air conditioning repair. Both of these parts are in the outside “condensing unit” of your HVAC system. With your system on if you don’t hear both running, or you have a tripped breaker, or you are hearing screeching or grinding, it’s possible that either your compressor or condenser fan motor are bad. These motors can fail in 3 ways typically:

1. Shorted to ground — This occurs when a winding (internal wiring that creates a magnetic field when power is applied) comes in contact with the case or ground. This will cause your breaker to trip and not reset.
2. Open winding — This is caused by a winding breaking and preventing power from properly flowing through the motor. It won’t trip a breaker but the motor is bad and will no longer turn.
3. Bad Bearings or Valves — The bearings allow the motor to turn freely with little friction. Bearings make a screeching or grinding noise when they go bad. The valves in a compressor (modern scroll compressors are sort of one big valve) go bad when they are no longer able to hold pressure. You may hear a hissing or whining sound as the refrigerant escapes around an area that should be sealed.

In none of these cases can you really do anything yourself so you’ll have to have a professional take a look.

Average repair cost in the industry for compressor:  $1200-1500 plus service charge

Average repair cost in the industry for condenser fan motor:  $700-900 plus service charge