In the thick of summer, window air conditioners can provide major relief in homes that don't have central HVAC systems. However, just like their permanent counterparts, window air conditioners are susceptible to damage.

With some basic troubleshooting, you may be able to fix common problems on your own, or at least be able to narrow down the list of potential problems and make an informed decision about whether replacement or repair is the best course of action.

The unit will not turn on

If your window A/C won't turn on, check if it's receiving power. Unplug it, then plug a different appliance into the same outlet. If it still doesn't turn on, check your circuit breaker. If the A/C has power, the problem could be related to a number of components within the unit, including the wiring, thermostat, compressor, selector switch or control board. These items should be repaired by a licensed HVAC technician.

The fan runs but does not blow cold air

If the fan is running but you can't feel any cold air blowing out, make sure the thermostat is set appropriately. Check the compressor motor, which is a small case inside the air conditioner. If it's humming continuously, the problem could be the condenser, evaporator or compressor. Otherwise, it could mean the motor is broken. These are all situations that require the help of a qualified technician.

The air is not cold enough

If the air is coming out cold but not cold enough, use a thermometer to see if there is a temperature difference of 15 degrees or more between air going into the unit and air coming out. If there is, you may be asking the unit to do more than it is capable of.

If the difference is less than 15 degrees, check the air damper. If it's open, it will bring in outside air, which is bad for efficiency. Also check the back cover, which many people forget to remove after the winter season. Finally, check the condensing coils, which are located on the warm end of the air conditioner. Remove the air conditioner's cover to access the coils, and clean them with a soft brush.

Water is leaking out of the unit

Window air conditioners collect water in their base. If the unit leaks, this may be because it wasn't installed properly. Tilt the A/C slightly back to allow the water to run off.