Before you call for service …
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 Causes | What to Do |
| Condenser 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 faulty. | 4. Call a professional. | |
| Uneven cooling | 1. Distribution system out of balance. | 1. Balance system. |
| Inadequate cooling | 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 cool | 1. Thermostat set too high. | 1. Lower thermostat setting 5°. |
| 2. Condenser dirty. | 2. Clean condenser coil and fins; if necessary, straighten fins. | |
| 3. Condenser unit blocked. | 3. Remove debris blocking condenser; 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. | 1. Clean condenser coil and fins. |
| 2. Condenser unit blocked. | 2. Remove debris blocking condenser; cut down weeds, grass, and vines. | |
| 3. Evaporator dirty. | 3. Clean evaporator. | |
| A dirty evaporator is a common problem | ||
| Condenser fan runs, but indoor fan coil blowing warm air (compressor not running) | Condenser fan runs, but indoor fan coil blowing warm air (compressor not running) | Check unit wiring and wiring |
| Water drips from unit. | Unit not properly leveled | Level the fan coil unit. |
| Condensate drain to condenser pan clogged | Clean condensate drain. | |
| Noisy fan operation | Fan striking | Check for proper positioning and clearance fans. |
| Loose fan or fan motor | Check for fan tightness on shaft. Check for loose fan | |
| Outside air entering the unit | Check for proper closing of outside air doors | |
| Air across condenser restricted | Check condenser air | |
| Dirty or blocked condenser | Check condenser for blocked dirt. Clean it | |
| Compressor or refrigerant system faulty | Call a professional. | |
| Evaporator ices over
| Clogged or dirty air filter | Clean or replace air filter. |
| Evaporator fan motor tripping on overload | – Check for overheated evaporator fan motor and tripping off on its internal overload / Call a professional. | |
| Unit operating at too low room temperature | If room temperature drops below 70F, the evaporator may ice over. | |
| Unit will not run
| Blown fuse / breaker trip | Check fuse / breaker |
| Broken or loose wiring | Check voltage at switch. If there is proper voltage at switch but no continuity thought it, replace switch / Call a professional. | |