Scenario: Compressor or Not?
Scenario: Your air conditioning is not working.
A service technician comes out and tells you that your air conditioning compressor (which is located outside) is no longer pumping refrigerant and needs to be replaced. This can be a major repair. Can you trust his diagnosis or not?
First let's talk about the different components of an air conditioning system: Most residential air conditioning systems are known as split-systems. A split system is where one component of the system is outside and the other component is inside, usually located in a closet or attic.The outside component is the condensing unit (which is where the compressor is located) and the inside component is the furnace/blower and evaporator coil. The air conditioning components are connected by copper tubing and run on 208/230 volts.
There are numerous ways you can check to see if it really is the compressor in your air conditioning unit. Ask the technician if he checked to see if the compressor has the proper voltage? He needs to tell you that the voltage is 208 or 230. If it is below this, then you could have a voltage loss problem instead of a compressor problem.
Did the technician Ohm out the compressor? There are three terminals on the compressor, usually located on the side of the air conditioning compressor. The terminals have wires running between them. They should show resistance between each terminal on an ohm meter. If you do not get a reading between any or all of the three terminals, the compressor could have a burned out winding or open winding as it is called (which basically means one of the wires between 2 terminals is burned open). Also the ohm meter should not show any resistance between any terminal and ground or the copper tubing. If it does show resistance between any terminal and a ground, the compressor could be shorted out. These two steps (ohming out the terminals and ohming to ground) should be done first. Then if the compressor passes these two tests, ask the technician if he replaced any starting components in the air conditioning unit? A simple start or run capacitor can cause the compressor not to run because the start or run capacitor has burned out due to heat or age. So again, the issue might not be your compressor at all but a simple starting component.
These are some of the questions you should ask your service technician before agreeing to the possible replacement of your compressor. The above advice is to inform you so that you can have a knowledgeable conversation with the service technician. This information is not provided for you to try and diagnose the air conditioning system yourself. The system is composed of moving mechanical parts and has very high voltage and you could be seriously hurt attempting repairs yourself. Let the professionals do their job.