A/C compressor clutch only engages when relay is jumped?

Hi,

I would be happy to help.

I suspect you tried switching the relay with a different one having the same part number, correct? If you haven't, try that first.

Now, the relay has 4 connector pins. If you remove the relay, you will see each pin has a number, 85, 86, 30, 87. Here is how this works.

The relay has a primary and secondary side. Pins 85 and 86 are the primary. Pins 30 and 87 are the secondary.

For the relay to actuate, power must be present at number 86 in the box and when you request the AC, connector pin 85 must provide a ground path via the engine control module. Once that happens, the primary is energized and becomes an electromagnet causing a switch on the secondary to close completing the secondary circuit.

At that point, connector pin 30, which has power at all times, allows power to run through the relay and out pin 87 to the compressor.

I hope that made sense. LOL

What I need you to do on this vehicle is determine where pin 86 is in the box. With the key on, check for power. Pin 30 should have power with the key on or off, so confirm that as well.

Next, If both pins have power (remember the key on for pin 86), we need to confirm there is a ground path being supplied via pin 85. To check for a ground, take your test light and connect the alligator clip end to the battery-positive cable. Probe the pin (85) in the box with the AC requested on. The test lamp should turn on.

Okay, I attached a pic below of the circuit so that you have a reference. Let me know if you are comfortable performing the tests I mentioned and what you find.

Take care,

Joe

See pic below.

Hi,

You are very welcome. I just hope it made sense. LOL Since you are able to jump the relay and compressor works, one of the things I mentioned is the problem.

Let me know.

Joe