A/C compressor clutch not engaging

FRUSTRATED73747

MEMBER
2005 MERCURY MARQUIS
4.6L
V8
2WD
AUTOMATIC
197,000 MILES

A/C compressor failure (came apart). Replaced compressor with new compressor. Also replaced condenser and accumulator. Flushed and vacuumed system. No leaks. Compressor clutch will not activate when jumping the cycling switch to allow me to charge with R134 and pag 46 oil. This is an automatic climate control system set on MAX A/C 60°F. What would cause clutch to not engage?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

Have you checked the fuses and the relay? If you look at pic 1 below, I circled the two of them. These are located in the battery junction box on the right side of the vehicle under the hood.

Pics 2 - 5 are the entire wiring schematic for the AC system. I added them so you can reference them if needed. I had to cut each pic in half to make them readable. However, I did overlap them so you can easily follow from one to the next.

Pic 6 shows the battery junction box. I highlighted the relay and fuse. Confirm there is power to and from the fuse in addition to just checking it. If there is a relay with the same part number, switch them. If there isn't, here is a link that explains how to test one:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If you haven't already, confirm there is no power to the clutch. If there is, you may just have a bad unit.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.

Images (Click to make bigger)