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AC Not Cooling? What to Check Before You Call for Repair

Five simple checks that fix many air conditioner problems, the warning signs that need a technician, what repairs typically involve, and how to avoid breakdowns.

An air conditioner that stops cooling on a hot day feels like an emergency. Sometimes it is. But a surprising number of “broken” systems have a simple cause you can fix yourself in a few minutes. Before you book a repair visit, work through these checks. And know the signs that mean you should stop and call a professional.

Five checks to do first

  1. Thermostat. Make sure it’s set to Cool, the target temperature is below the room temperature, and the fan is on Auto. If it runs on batteries, replace them; a blank or flickering display is a common culprit.
  2. Circuit breaker. Central air systems usually have a breaker in the main panel and a disconnect switch near the outdoor unit. If a breaker has tripped, reset it once. If it trips again, leave it off and call a technician.
  3. Air filter. A clogged filter chokes airflow, makes the system work harder and can cause the indoor coil to freeze. Check it monthly in summer and replace it when it looks grey or dusty.
  4. Outdoor unit. Clear leaves, grass clippings and anything stored against it. The unit needs about two feet of open space around it to shed heat.
  5. Vents and registers. Make sure supply vents are open and not blocked by furniture or rugs.

Give the system 15 to 30 minutes after a fix before judging the result.

Signs you need a technician

Stop troubleshooting and call for repair if you notice:

  • Ice on the refrigerant lines or indoor coil. Turn the cooling off and run only the fan to thaw it, then call. Ice often points to low refrigerant or an airflow problem.
  • Water leaking around the indoor unit, which can mean a blocked condensate drain or a cracked drain pan.
  • Grinding, squealing or banging noises from either unit.
  • A burning smell, or a breaker that trips repeatedly. Turn the system off.
  • The outdoor fan not spinning while the system is calling for cooling.
  • Short cycling: the system turns on and off every few minutes.

Refrigerant work requires a certified technician by law in the US, so a system that needs recharging isn’t a DIY job.

What common repairs involve

  • Capacitor replacement. Capacitors help the motors start. A failed one is among the most common and least expensive repairs.
  • Contactor replacement. This switch in the outdoor unit wears out over time.
  • Refrigerant leak repair. The technician has to find and fix the leak, not just top up the system.
  • Fan motor or blower motor replacement.
  • Clearing a blocked condensate drain.
  • Compressor failure. The most expensive repair. On an older system, replacing the whole unit is often the better investment.

Ask for a written estimate before work starts, and ask whether the part is covered by a manufacturer’s warranty.

Repair or replace?

A rough rule many technicians use: if the system is more than 10 to 15 years old and the repair would cost a large share of a new system, replacement is usually worth considering. Newer systems are more efficient and use newer refrigerants; older units that use R-22, which was phased out in the US, are increasingly expensive to service.

Preventing breakdowns

  • Replace or clean the filter regularly.
  • Book a professional tune-up each spring, before the hot weather.
  • Keep the outdoor unit clear and hose off the fins gently once a season.
  • Pour a cup of diluted vinegar into the condensate drain line access, if your system has one, to prevent clogs.
  • Use a programmable thermostat to avoid running the system flat out all day.

The short version

Check the thermostat, breaker, filter, outdoor unit and vents first. If the problem involves ice, leaks, strange noises, burning smells or repeated breaker trips, switch the system off and call a licensed HVAC technician.

Sources