Fix it
Window AC Not Working? Fixes (2026)
Why your window AC is not cooling: filters, breakers, icing, and sizing mistakes, in fix order.
A window AC that is not cooling is usually suffering from restricted airflow, an electrical issue, or a sizing mismatch, not a dead compressor. Work through these fixes before calling for service.
AC runs but barely cools the room
Clean the filter first. A clogged filter is the number-one cause of weak cooling: slide it out (front-access on the Frigidaire, GE, and LG) and wash it with mild soap and water, drying fully before reinstalling. Next, check that the thermostat is set at least a few degrees below room temperature and the mode is Cool, not Fan or Dry. If cooling is still weak with a clean filter, the unit may be undersized for the room, compare your square footage against the BTU rating.
AC will not turn on at all
Check power in order: confirm the outlet works with another device, check the breaker panel for a tripped breaker (window ACs draw near circuit limits, especially 12,000+ BTU units sharing a circuit), and inspect the unit's power cord for the reset button many ACs include on the plug. If the breaker trips repeatedly, the circuit is overloaded: move other devices off it or have an electrician add a dedicated circuit. Never use an extension cord.
Ice forming on the coils or front grille
Restore airflow. Turn the unit to Fan-only mode to thaw the ice, then clean or replace the filter. Icing with a clean filter in normal weather points to low refrigerant from a leak, which needs professional service, or to running the AC when it is below about 60°F outside, which window units are not designed for. Do not chip ice off the coils; bent fins restrict airflow permanently.
Room cools but stays humid and clammy
The unit is oversized for the room. It cools the air so quickly the compressor shuts off before running long enough to dehumidify. Short-term: run the fan on low to extend cycles, and use Dry mode if available. Long-term: this is a sizing problem, and the correct fix is a smaller unit matched to the room. Inverter models (LG, Midea U) mitigate this by slowing down instead of shutting off, which is one of their real advantages.
Questions, answered
Water is dripping inside instead of outside. What is wrong?
The unit is not tilted correctly. Window ACs must tilt slightly toward the outside so condensate drains out the back. If it is level or tilted inward, water pools and drips inside. Re-seat the unit with a slight outward tilt, about a quarter-inch drop from front to back.
The AC smells musty when it starts. How do I fix it?
That is microbial growth on the evaporator coils and drain pan from standing moisture. Clean the filter, then run the unit on Fan-only for an hour to dry the coils. Persistent odor needs a no-rinse evaporator coil cleaner sprayed on the coils through the front grille with the unit off.