To troubleshoot an air conditioner thermostat, identify the type of thermostat that is in use, check that the unit is receiving power and ensure the unit is installed properly. Most thermostats are either electromechanical or electronic, which affect how the room's temperature is determined.
There are several steps needed to perform common troubleshooting on either thermostat type.
- Replace the filters
- Check the power
- Inspect the thermostat's interior
- Ensure the unit is level
- Wiggle the anticipator
- Replace the unit or consult a professional
Before troubleshooting the thermostat, check the filters and replace if necessary, as dirty filters are a common culprit.
Make sure the thermostat is receiving power, either through batteries or through the main electrical panel. Use a voltmeter to test the power. Also make sure the thermostat itself is on and set to "cool."
Ensure the power is off for this step, and remove the thermostat cover to reveal the interior wires. If the interior is dusty or dirty, use a small brush or a can of compressed air to clear away the debris. Then visually inspect all of the wires to ensure they are all attached properly and are in good shape. Tighten any loose wires or screws and clean or replace any corroded wires.
Older thermostats need to be level for the temperature sensor to operate properly. Use a level to ensure the thermostat is installed properly to the wall.
Gently push the metal tab, called the anticipator, that is mounted on the round dial. If this does not solve the issue, the anticipator may need an adjustment from a professional.
If common troubleshooting tips do not solve the issue, price out replacing the unit versus consulting a professional and proceed as necessary.