AC clutch will not engage

TUMULTOUS

MEMBER
2004 FORD EXPEDITION
4.6L
V8
2WD
AUTOMATIC
177,000 MILES

The ac in my wife's expedition went out at the end of last summer. The ac worked fine but every time I turned it on it made an awful grinding sound until it finally quit. I got it home and popped the hood and turned the ac on and the clutch would spin a little bit and stop. I unhooked the power to the compressor by just unplugging the power connection so we could have heat this winter. Well, yesterday I replaced the clutch, the bearing and the pulley and got it within Ford factory specifications of the air gap and used only genuine factory parts. Hook the power back to it and tried turning the ac on and the clutch still wont engage. Could it be the relay fuse for the compressor? Or just completely recharged? I checked all the fuses and replaced the ones that were blown also. Please help.

Wednesday, April 1st, 2015 AT 6:15 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If the compressor will not engage at all, let's start with jumping the relay and see if it will even kick on when you control the relay.

If it doesn't then we most likely have a failed compressor all together.

However, this does sound like a power issue so it could be the relay.

Here are a couple of guides that will help with this:

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

So, what we need to do is jump 30 to 87 in the relay using the diagram below. If the compressor comes on, then we need to check power at the relay on 30 and 86. If you have 12 volts then we need to check the ground on 85. If there is no ground, then the PCM is not turning the compressor on.

This could be due to a pressure issue or pressure switch issue, so we need to check the pressure and find out if it is low.

Here is a guide that will help with this:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Please see the diagram below and let me know what you find. Thanks

Image (Click to make bigger)