Testing an Air Compressor Pressure Switch
The air conditioner on your vehicle has an air compressor pressure switch, to regulate the pressure of the refrigerant. When this air compressor pressure switch is not working correctly, the air conditioner will either not work at all, or not create enough cold air. If you are having problems with your air conditioner, here are some steps to take in testing the air compressor pressure switch.
Step 1: Disconnect Battery
Disconnect the battery terminals before working on the air conditioner.
Step 2: Remove Cover for Compressor Unit
There should only be 1 or 2 screws holding the cover on the unit. Remove these with a slotted screwdriver.
Step 3: Disconnect Terminal Wires
Locate the wires to the switch and disconnect them. They will either be a blue or brown color.
Step 4: Test Switch with Air
Once you have access to the pressure switch, blow some air on it from an air compressor or compressed air can.
Step 5: Connect Ohm Meter
With the air applied to the switch, connect the leads of the Ohm meter to each of the wires. If the pressure switch closes when the air is applied, the meter will read zero. If not, the meter will read 'OL' which means open circuit.
Step 6: Make Adjustments
If you find that the pressure switch is not working correctly, adjust the set screw or replace it.