Common AC Problems and How to Fix Them

Q: Why is my AC blowing warm air?

The most common causes are a dirty filter, low refrigerant, or a faulty compressor. Start by checking and cleaning the filter. If the problem persists, call a technician to check refrigerant levels.

Q: Why is my AC leaking water inside?

Usually caused by a clogged condensate drain line, a dirty filter causing ice buildup, or improper installation angle (for window units).

Q: Why is my AC making a loud noise?

Buzzing usually indicates an electrical issue. Rattling suggests loose parts. Grinding means motor bearings are failing. Hissing points to a refrigerant leak.

Before calling a technician, try these troubleshooting steps. Many common AC problems have simple fixes that can save you $150-$300 in service calls.

Why Is My AC Blowing Warm Air?

Check the thermostat — make sure it is set to "cool" mode, not "fan only"
Check the filter — a clogged filter restricts airflow and reduces cooling
Check the outdoor unit — clear any debris blocking the condenser
Check for ice — if the evaporator coil is frozen, turn off cooling and run fan only for 2-3 hours to thaw
If none of these help, you likely have low refrigerant — call a technician

Why Is My AC Leaking Water Inside?

Window AC: Check that the unit tilts slightly backward (1/2 inch). Clean the drain hole with a thin wire
Central/Mini-Split: The condensate drain line is probably clogged. See our drainage guide for clearing instructions
Frozen coil melting: If the coil was frozen and then thaws, water overflows the drain pan. Fix the root cause (dirty filter, low refrigerant)

Why Is My AC Making a Loud Noise?

Rattling: Loose screws, panels, or debris in the unit. Tighten fasteners and check for foreign objects
Buzzing: Electrical issue (capacitor, contactor, or loose wiring). Turn off and call a technician
Grinding: Motor bearings are failing. Needs professional repair
Hissing: Refrigerant leak. Turn off immediately and call a technician
Clicking (repeated): Compressor relay issue. Professional repair needed

Why Does My AC Smell Bad?

Musty/moldy: Mold or mildew on the evaporator coil or in the drain pan. Clean with a coil cleaner spray and flush the drain line
Burning: Electrical problem or overheating motor. Turn off immediately
Chemical/sweet: Possible refrigerant leak. Ventilate the room and call a technician

Why Is My AC Short Cycling (Turning On and Off Frequently)?

Oversized unit for the room (too many BTUs)
Dirty filter restricting airflow
Thermostat in direct sunlight or near a heat source
Low refrigerant
Faulty compressor or capacitor