Troubleshooting Central Air Conditioners

Central air conditions will need some professional maintenance, but there are many minor problems that you can easily fix yourself. If your central a/c unit isn’t working properly, look for the problem you’re experiencing on this chart and see if it’s a do-it-yourself job.

Problem Possible cause Solution
doesn’t run
1. No power. 1. Check for blown fuses or tripped
circuit breakers at main entrance
panel or at separate entrance
panel; restore circuit.
2. Thermostat set
too high.
2. Lower thermostat setting 5°.
3. Motor faulty. 3. Call a professional.
4. Compressor
4. Call a professional.
Uneven cooling 1. Distribution
system out of
1. Balance system.
1. Thermostat set
too high.
1. Lower thermostat setting 5°.
2. Evaporator dirty. 2. Clean evaporator
3. Unit too small. 3. Replace with larger unit;
call a professional.
Unit doesn’t 1. Thermostat set 1. Lower thermostat setting 5°.
cool     too high.
2. Condenser dirty. 2. Clean condenser coil and fins;
    if necessary, straighten fins.
3. Condenser unit 3. Remove debris blocking condenser;
    blocked.     cut down weeds, grass, and vines.
4. Evaporator dirty. 4. Clean evaporator.
5. Compressor faulty. 5. Call a professional.
6. Not enough
refrigerant in system.
6. Call a professional.
Condenser unit
turns on and
off repeatedly
1. Condenser dirty.
2. Condenser unit
1. Clean condenser coil and fins.
2. Remove debris blocking condenser;
cut down weeds, grass, and vines.
3. Evaporator dirty. 3. Clean evaporator.

A dirty evaporator is a common problem. On the next page you’ll learn how to access the evaporator and clean it properly.