How to Wire an A/C Compressor in a Car

by Eli Laurens

The automotive compressor is wired to a car's electrical system through the wiring harness, connected primarily by an electric clutch. This clutch has a power lead that can also serve to power a throttle solenoid, raising the engine idle on older vehicles to compensate for the added drain of the compressor. The average backyard mechanic can wire a compressor to a car in about 10 minutes.

Step 1

Disconnect the battery by turning the positive terminal bolt counterclockwise. Lay the terminal aside, away from the battery.

Step 2

Check the mount bolts for the compressor, or any ground lead wires coming from the body. The mount bolts on most models serves as the ground for the unit, and tight mount bolts mean a solid negative power coupling.

Step 3

Consult the wiring diagram for the model, locating the green wire that is coming from the throttle area. Typically, a solenoid attached to the throttle is activated when the system is turned on, and the lead from this component will power the compressor clutch. Most models use a green wire for this connection, as it has become an industry standard. This wire attaches to the compressor at a socket or protruding blade connector. The wire will have an adapter plug on the end of it, and if it does not, one must be attached to it.

Step 4

Make an even cut on the green wire, with enough lead to reach the compressor; placing the wire into the cutter's blades and pressing the handles together quickly and firmly will cut the wire. Use the stripping tool to remove about an inch of the insulation from the end of the wire. Press this exposed end into the adapter plug suited to the model. Using the end of the stripper tool, crimp the wire into the connector with a firm grip.