Start your window air conditioner troubleshooting with
checking the different modes of operation to see which components
operate. Turn the unit fan to on and the cool and heat modes off. If the
fan does not operate, check the power supply to the unit. Check to see
if the breaker or fuse for the unit is tripped. If the breaker/fuse is
tripped, check to make sure that it is the proper size circuit for the
unit you have. On some units, there is a current interrupter on the
power cord to the unit. Check to see if it is tripped by pushing the
reset button.
If the circuit is the proper size, then you can go ahead and
reset the breaker/fuse. If it trips again, then you require further
troubleshooting. Shut the power off and check all of the wiring in the
unit to make sure that none of the connections is loose or damaged.
If the fan does not operate but the fuse/breaker is not tripped, you should check the run capacitor
for the fan and compressor. If the capacitor is good but the fan motor
does not operate, you can check the fan switch and the fan motor.
Ensure that the fan blades spin freely.
If the fan motor operates but the compressor does not start, change the capacitor but first you should
feel the compressor with your hand. If it is very hot, then you should
allow it to cool.
Then, you should attempt to start the unit in the cooling mode.
As you do so, listen for a clicking sound which is an indication that it
is attempting to start. If the compressor starts but does not cool
properly, the unit may be low on refrigerant.
If the compressor attempts to start but shuts off very quickly,
the compressor could be bad. You could try installing a "Hard Start"
If the compressor does not attempt to start, ensure that the
thermostat is set below room temperature. On units with a mechanical
control, you will hear a click when you adjust the temperature. That is
an indication that the thermostat is working properly.