How To Troubleshoot AC Failure
What to Check Before You Call
When your air conditioner isn’t working, you don’t need to get hot under the collar. There are a few things you can safely check yourself. Even if you can’t do the repair, you can eliminate some possible causes of the problem so a professional technician spends less time on diagnosis and more quickly solves the problem to get your AC back up and running.
In this post, we cover the checks that are safe to do yourself and what to leave to a technician.
Initial Diagnosis
Eliminate the Furnace
Make sure the problem isn’t the furnace. Set the thermostat to AC mode and lower the temperature. If the furnace fan comes on, that’s good. It means the problem most likely is not the furnace itself. You can read on to see if there’s anything you can do to fix the AC unit.
If the fan doesn’t run, check the furnace breaker and the furnace switch. If the fan still doesn’t come on, the problem is in the furnace or air handler. Call an AC repair company.
Check the Outside Condensing Unit
Are the compressor and fan in the outside condensing unit running? If you hear a sound like a refrigerator running, then it is. If it is and you still don’t have cooling, you may want to stop here and call an experienced AC person.
If the compressor and fan aren’t running, try the checks below.
Try These Checks First
These checks are safe for a homeowner, and each one rules out a common cause. Work through them in order:
- Thermostat. Make sure it is set to Cool, the set point is below the room temperature, and the fan is on Auto. Replace the batteries if it has them.
- Breakers and the outdoor disconnect. Check that the breakers for the furnace or air handler and for the outdoor unit are on, and that the disconnect switch next to the outdoor unit is on. If a breaker trips again after you reset it, stop and call a technician.
- Air filter. A clogged filter can cut airflow enough to freeze the indoor coil. Replace it. If you see ice on the refrigerant lines, turn the system off and let it thaw before you try again.
- Outdoor unit. Clear leaves, plants and debris from around the unit so air can flow freely. With the power off at the breaker, you can rinse the coil gently with a garden hose, spraying from the inside out.
- Condensate overflow switch. Many systems shut off cooling when the condensate drain backs up. If the drain pan near the indoor unit holds water, the drain line is probably clogged, and a technician can clear it.
Capacitors hold a dangerous charge even with the power off. Leave the electrical parts in the outdoor unit, the refrigerant and the compressor to a technician.
If none of these checks brings the cooling back, or a breaker keeps tripping, call for service. Telling the technician what you already checked saves time on the diagnosis.
AC Overview
It helps to know how a central air conditioning system works. There are a few major components:
- Outside condensing unit
- Evaporator coil (aka A-coil) situated in the furnace air handler
- Furnace or indoor air handler
- Thermostat
Here’s how these components work together:
Refrigerant in the A-coil absorbs heat from inside your home and transports it to the outdoor condensing unit. The condensing unit fan blows outside air across the condensing coil to carry that heat away, and the cooled refrigerant flows back to the indoor coil.
There are no parts in the A-coil. Only a professional AC technician can service the A-coil.
The condensing unit houses a compressor, which also only a professional AC technician can service.
The parts that fail most often in the outside condensing unit are:
- AC contactor. This is a mechanical relay that employs low-voltage power from the thermostat to switch high amperage current to the compressor and condenser fan.
- Start/run capacitor(s). The capacitor stores electricity and releases it as needed to provide extra power to the compressor and condenser and minimize voltage fluctuations that can damage them.
- Condenser fan motor.
Your AC Partner
If all this seems a bit overwhelming, we here at Ongaro & Sons can quickly help you get your cool back. We’ve been in business since 1932, providing high-quality service using only the highest quality equipment. Ongaro & Sons is a licensed state contractor and our qualified technicians are fully insured. Our 100% guarantee ensures your complete satisfaction.
Contact Ongaro & Sons today if you need an AC repair, or if you are considering a new AC system. We look forward to serving you so that you can maintain your cool.
