Air conditioners can develop issues over time, but many problems have simple DIY fixes before calling a professional. Here are 10 common AC problems and how you can troubleshoot them yourself.
1. AC Not Turning On
Possible Causes:
Tripped circuit breaker
Blown fuse
Faulty thermostat
Power switch turned off
How to Fix:
✔ Check the circuit breaker and reset if tripped.
✔ Replace a blown fuse.
✔ Ensure the thermostat is set to “Cool” and has fresh batteries.
✔ Verify the outdoor unit’s power switch is on.
2. Weak Airflow
Possible Causes:
Clogged air filter
Blocked vents or ducts
Faulty blower fan
How to Fix:
✔ Replace or clean the air filter (every 1-3 months).
✔ Ensure vents are open and unobstructed.
✔ Check the blower fan for debris or damage.
3. AC Blowing Warm Air
Possible Causes:
Dirty air filter
Low refrigerant levels
Frozen evaporator coil
Outdoor unit issues
How to Fix:
✔ Replace the air filter.
✔ Check if the outdoor unit is running (if not, reset the breaker).
✔ If the evaporator coil is frozen, turn off the AC and let it thaw.
✔ If refrigerant is low, call a professional (handling refrigerant requires certification).
4. AC Leaking Water
Possible Causes:
Clogged condensate drain line
Frozen evaporator coil
Broken condensate pump
How to Fix:
✔ Unclog the drain line with a wet/dry vacuum or bleach solution.
✔ If the coil is frozen, turn off the AC and let it thaw.
✔ Check the condensate pump (if installed) for proper operation.
5. AC Making Strange Noises
Possible Causes:
Banging: Loose or broken parts
Squealing: Worn-out belt or motor bearings
Clicking: Faulty relay or electrical issue
Hissing: Refrigerant leak
How to Fix:
✔ Tighten loose screws or bolts.
✔ Replace a worn-out belt (older units).
✔ If refrigerant is leaking, call a professional.
6. AC Short Cycling (Turning On/Off Frequently)
Possible Causes:
Dirty air filter
Low refrigerant
Oversized AC unit
Faulty thermostat
How to Fix:
✔ Clean or replace the air filter.
✔ Check thermostat placement (avoid heat sources).
✔ If the unit is too large, consult an HVAC technician.
7. Frozen Evaporator Coil
Possible Causes:
Low refrigerant
Poor airflow (dirty filter or blocked vents)
Faulty blower motor
How to Fix:
✔ Turn off the AC and let the ice melt.
✔ Replace the air filter.
✔ Check refrigerant levels (call a pro if low).
8. AC Smells Bad
Possible Causes:
Musty smell: Mold in the ducts or drain pan
Burning smell: Electrical issue
Rotten egg smell: Dead animal in the ductwork
How to Fix:
✔ Clean the drain line with bleach.
✔ Replace the air filter.
✔ If electrical, turn off the AC and call a technician.
9. Thermostat Not Working
Possible Causes:
Dead batteries
Incorrect settings
Loose wiring
How to Fix:
✔ Replace thermostat batteries.
✔ Ensure it’s set to “Cool” and the right temperature.
✔ Check wiring connections.
10. High Energy Bills
Possible Causes:
Dirty air filter
Leaky ducts
Old, inefficient AC unit
How to Fix:
✔ Replace the air filter regularly.
✔ Seal duct leaks with foil tape or mastic.
✔ Consider upgrading to an energy-efficient model.