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96 Mystique A/C clutch problem
07-19-2010, 05:08 PM
Post: #1
96 Mystique A/C clutch problem
Greetings.

I have a 1996 Mercury Mystique with non-working A/C. When I got the car, the low pressure cutout switch had been replaced, and the compressor clutch relay had been removed and was left lying sideways in the fuse compartment.

The A/C clutch will engage if the relay contacts are jumpered at the socket, but not when the relay is installed, and A/C is selected. When the clutch is engaged manually in this manner, the engine idle drops (seems the computer doesn't know to increase the idle speed to compensate) There is no voltage on either of the relay coil terminals in the socket, and one side shows a short to ground (I would expect by design).

System pressure is good.

Thoughts? Anyone have a wiring diagram available?

Thanks in advance. Smile
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07-19-2010, 10:08 PM (This post was last modified: 07-19-2010 10:10 PM by Rupe.)
Post: #2
RE: 96 Mystique A/C clutch problem
Not familiar enough with this vehicle to give step by step advice but have found some weird problems over the years.

Does it have a high pressure switch? (sometimes on the compressor)

Does the power for that relay come from the computer or the AC selector switch? (I have seem a bad ECM keep the AC off)

Is there a blown fuse? (check with a test light)

Have you had a set of AC gauges in it to determine the pressures are good while running?

Are there any codes in storage?
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07-20-2010, 08:44 AM
Post: #3
RE: 96 Mystique A/C clutch problem
(07-19-2010 10:08 PM)Rupe Wrote:  Not familiar enough with this vehicle to give step by step advice but have found some weird problems over the years.

Does it have a high pressure switch? (sometimes on the compressor)

Does the power for that relay come from the computer or the AC selector switch? (I have seem a bad ECM keep the AC off)

Is there a blown fuse? (check with a test light)

Have you had a set of AC gauges in it to determine the pressures are good while running?

Are there any codes in storage?

Did not see a high pressure switch, and not sure what's driving the relay coil (wiring diagram would help with these)

All fuses are good

Gauges show normal pressures both running and not for ambient temp

No codes Sad
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07-20-2010, 09:14 AM
Post: #4
RE: 96 Mystique A/C clutch problem
Did some poking around the net for a diagram and anything I have found has been such low resolution it's usless when blown up enough to see anything.

Have you tried the local library for a repair manual or asking at the local dealer to see if they will print you a page?

Sorry I can't be of more help.
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07-20-2010, 11:29 AM
Post: #5
RE: 96 Mystique A/C clutch problem
(07-20-2010 09:14 AM)Rupe Wrote:  Did some poking around the net for a diagram and anything I have found has been such low resolution it's usless when blown up enough to see anything.

Have you tried the local library for a repair manual or asking at the local dealer to see if they will print you a page?

Sorry I can't be of more help.

Thanks for trying - I poked around also and came up with nada. The library is a good idea that I hadn't thought of, or I might just spring for the $30 service manual. :|

Someone else posted a snippet of a diagram for the blower fan motor in the Ford forum here, hoping he'd pop in and offer the rest of the diagram Smile
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07-20-2010, 01:52 PM
Post: #6
RE: 96 Mystique A/C clutch problem
The plot thickens...

I found the vehicle wiring diagrams at autozone.com, believe it or not. They do not, however, contain any reference to the A/C compressor clutch circuit, only the A/C high pressure cutout switch and three wires from the PCM labeled 'to a/c system'. :/
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07-20-2010, 10:16 PM
Post: #7
RE: problem solved
A relay socket contact had dislodged inside the fuse box housing. The battery and fuse box needed to be removed, accessed from below, and the contact re-seated in the relay socket.
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