Many air conditioner problems aren't with the unit itself, but with the thermostat. The thermostat is more than just the place where you adjust the temperature in your home, it is the main control center for your entire air conditioning system. It tells your AC when to come on, how long to run, and when to turn off. The following guide can help you diagnose thermostat problems so you know when to call in an air conditioning repair professional.
Problem #1: The AC Won't Come On
Check the thermostat first and make sure that it is one and set to a temperature lower than what it currently is in the home. Next, verify that the breaker in the circuit box that is attached to the thermostat isn't tripped. You can also use voltometer to make sure power is reaching the thermostat.
Some thermostats require a battery back-up, so simply switching the batteries will get them started again. Digital thermostats may also show error codes, which you can look up in the owner's manual to discover the issue. If the thermostat isn't working, you may need to replace it or bring in a tech to verify it is the root of the problem.
Problem #2: Your Home Is Too Cool
If the AC continues to run long after your home has reached the temperature set on the thermostat, you will need to do some troubleshooting. First, set an outside thermometer near the thermostat to verify that the air temperature in this specific area has lowered to the set amount. In some cases, thermostats are located on a warm wall, such as an exterior wall, one in direct sunshine, or one that backs up to the oven, which causes the thermostat to register a higher reading than that in the rest of the home. If this isn't the case, try reprogramming the thermostat. If the AC still continues to run, it is time to replace the thermostat.
Problem #3: Thermostat Works Only in Fits and Starts
If your thermostat sometimes works perfectly, and at other times keeps your home too cool or too warm, there are several reasons to look into. First, make sure the thermostat is level using a standard household level. Poor performance is normal in an unlevel thermostat because it misaligns the temperature gauge inside.
Next, make sure the thermostat is clean. Remove the cover and dust carefully inside, using canned air or a small handheld vacuum with an electronics attachment. If both leveling and cleaning the thermostat fail to fix the problem, call in a professional AC technician to repair or replace it.