Homeowners often fear that the window air conditioner will stop working when a heat wave strikes. But a window air conditioner that won't turn off without pulling the plug can become equally problematic due to frigid temperatures and rising electric bills.
There are a few potential causes for a window air conditioner that won't turn off. If you don't have any air conditioner repair experience, you might want to leave the actual fixes to a certified air conditioning services technician.
Dirty Condenser Coils
The condenser coils are the first stop for the refrigerant that powers the cooling system. Gas refrigerant enters the coils and is changed into a liquid, which is then passed to the evaporator coils, which become cold while changing the liquid back to a gas. Those cold evaporator coils are what makes your air cold.
But it's the condenser coils that get the cooling party started. If the coils become dirty, the air conditioner is no longer able to adequately process the heat from the incoming air that needs to cool over the evaporator coils. So dirty coils mean that the system is running less efficiently and isn't cooling your air to the level indicated on the thermostat. Because of this difference in performance versus expectation, the compressor stays running constantly to try and make up the difference.
Condenser coils can be cleaned using a no-rinse foam cleaner from the hardware store. Follow the package directions and use your owner's manual to find the coils in your window air conditioner.
Thermostat issues can cause the air conditioner to run constantly because the system doesn't think the air is cold enough. Common thermostat issues involve the thermostat control panel and/or the thermistor, a sensor on the control board that reads the room temperature.
All of these fixes require electrical knowledge. If you have that knowledge, consult your owner's manual for instructions for your particular unit. Otherwise, leave the fix to a HVAC technician as improper electrical handling can crash your unit permanently.
Control Board Issues
There is a primary control board that serves as the brain of your unit.
The temperature control board sends an electrical signal to the fan and compressor, so if the board fails to work properly, the compressor can never get the signal to turn off once the air is sufficiently cold. This board might also be called a main control board or relay board, depending on your unit.
Again, you want to consult an HVAC technician for this fix if you have no electrical experience. If the board is completely broken, it might be cheaper to buy a new unit than to replace the part.
To learn more, contact a company like Metro Air.