When checking out a window air conditioner unit, the voltage might need to be checked both before and after the thermostat. Sometimes you can be getting voltage ‘to’ the thermostat, but not ‘from’ it. That means you might need to replace the thermostat. This is one of the most common problems, so checking it first is a good idea.
The worst possibility of all – having a total compressor failure.
Usually when this happens the air conditioner compressor locked up. That means it won’t be able to turn once you supply power to it. Lack of lubrication or overheating are usually the causes of compressor failure. When the outdoor coil around your compressor becomes clogged with grass, leaves, and dirt, the result can be overheating. Your next move should be to wash out your outdoor coil.
Another place to look at is your fan motor voltage. Fans on the window air units run both your indoor blower and your condenser fan. When that motor fails your compressor might run for a little while, but it will eventually overheat and shut down. If you let it continue to operate in that fashion, you will end up having compressor failure. For larger window ACs this motor can be replaced fairly economically. However, in the smaller units the replacement costs can be more than the cost of purchasing a brand new unit.
Central ACs in the home can be a bit more complex. They have a lot more things that may go wrong. Just like with the window ac, the thermostats on these can be problematic as well. A central AC thermostat only has 24 volts running to it. That means no use looking for any high voltage there.
On some of these units the voltage comes from your outdoor unit, while on others it can be supplied via the indoor air handler or the furnace. Most central home ACs are supplied via the indoor air handler or furnace. If your AC is only for cooling, then it usually carries just 2 wires that run to your condenser unit. Be sure that you’ve got 24 volts running across those wires.
The next thing you want to check out is your indoor blower. When your thermostat is calling for cool, then your indoor blower ought to be running. If you have no air moving across your indoor cooling coil, then before long you’ll have a huge block of ice forming on your coil. There are a couple of reasons why this can happen. Your indoor blower isn’t working, your air flow is restricted and is not allowing any air to move across your coil. Clogged air filters will cause this too. It could also mean that your outdoor condenser unit lost its charge of refrigerant.
This should be a regular part of your yearly maintenance. Use a good coil cleaner and just water. Doing this will help you avoid experiencing compressor failure, as well as keeping your unit running at its optimum efficiency. Changing your AC compressor can be the type of job that requires specialized equipment. It should be handled by a professional who holds a current refrigeration license.