Air Conditioner Won’t Turn On? Here’s What To Check
How To Troubleshooting Your Central AC
If your central air conditioner will not turn on, or has suddenly stopped working and cannot be restarted, there are several things to check yourself before calling us for service. Here is where to start:
- First, ensure the thermostat is set to the “COOL” setting and that not been unintentionally set to “OFF” or “HEAT”. Look to see if there any warning or error messages on the thermostat display. If there are, consult the owner’s manual for the thermostat to see if there are steps you can take to resolve the error.
- If the thermostat appears to be working normally, check the thermostat’s “set” temperature is set lower than the room temperature where the sensor is located. You may need to lower the set temperature a few degrees before it will turn on.
- Check that the air conditioner’s external safety switch is set to the “ON” position. This switch can typically be found on an exterior wall near the AC condensing unit.
- Check that the circuit breaker that controls the air conditioning compressor and the circuit breaker that controls the furnace blower or air handler, are in the “ON” position. If a circuit breaker has tripped, reset the circuit breaker. If the circuit breaker cannot be reset, do not attempt to reset it again. Have a qualified HVAC technician or electrician check the circuit to determine the cause of the malfunction.
- Is the furnace air filter dirty? An excessively dirty air filter can obstruct airflow, causing the blower to shut down as a safety measure. Replace the filter if it appears to be clogged with dirt.
- Finally, the AC unit may not turn on due to an excessive build-up of water from condensation, which can occur when the drain pan or drain line is clogged with mold, algae, or dirt. Check the drain pan and clear any obstruction from the drain line if necessary.
If you have tried the steps above and your central air conditioner still won’t turn on, call Central Heating Cooling Plumbing and Electrical for AC service. Our cooling system experts can troubleshoot your system and get the AC back up and running quickly.