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Hi there - Air con compressor clutch not pulling in & I've traced the problem to the ground line of the air con relay coil - if I earth this line the compressor cuts in & run fine.

So am looking for a wiring diagram to help me trace the issue thru this line - which I think goes thru' the switch in the dashboard, the LP air-con switch and the HP air-con switch.

The car is 2004 1.6 LX Estate.

Haynes manual has just about every wiring circuit (including cruise control FFS !) but not the air con - amazing considering it's fitted to the majority of Mk1s !

ta

Jools
 

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2004 Focus Wagon, Zetec DOHC, Auto
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On the US models it is a black/yellow wire on the ground side of the relay coil which goes to the PCM.
 

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Discussion Starter #3
Thanks Focusknot - I was thinking the line is earthed via hardwiring which going thru the dash switch & the two pressure switches - but if it goes back to the PCM than (I assume) that means it's earthed by the module which takes the signals from the dash and pressure switches and (via the software) earths the line to switch the air con on & off - is that right ?
In which case I won't be able to "trace" the wire - all i can do is check the function of each part and trust the SW is doing what it should do ?
Ta
Jools
 

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^^Correct. The PCM makes decisions based upon the various A/C controls and sensors, and turns the relay on/off.

Common items that prevent A/C clutch operation are the blower motor resistor block (big clue there if lowest speed does not work), low refrigerant pressure, and the A/C dash switch.
 

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Discussion Starter #5
Thanks - will get my meter and power probe out and start looking !
Don't think it's the A/C clutch as when I earth the problematic line the AC compressor cuts in & runs fine.
The Blower works on all speeds.
The light on the dash switch comes on when it's pressed ?
So I guess th likely culprits are the LP & HP switches - either one of them has failed or a connection has corroded.
Do you have any info on the switches that might help to eliminate/identify the fault ?
ta
Jools
 

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Hi there - Air con compressor clutch not pulling in & I've traced the problem to the ground line of the air con relay coil - if I earth this line the compressor cuts in & run fine.

So am looking for a wiring diagram to help me trace the issue thru this line - which I think goes thru' the switch in the dashboard, the LP air-con switch and the HP air-con switch.

The car is 2004 1.6 LX Estate.

Haynes manual has just about every wiring circuit (including cruise control FFS !) but not the air con - amazing considering it's fitted to the majority of Mk1s !

ta

Jools
have u tried taking ur car to service? I would not recommend you doing that alone (trust my experience lol) had the same issue as yours and there were some sticky wires that I could not manage to unite, yet wasted so much time and in the end i just broke it lol. Thanks to guys from socool.sg that answered to my calls and arrived at my place to help me. Since then I Actually never try to fix such kind of minimal stuff individually, because you can screw it up. I guess that's why you learn in school, before going driving lol.
 

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Have you tried reading up on blogs to see if you have an answer? Just to point you in the right direcirton so you know the cost and where to go .

Like the other guys said. Take it to service. Don't do it alone lol.
 

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Get lost you two spammers.
 
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