air conditioning compressor clutch
05-20-2012, 09:48 AM
#11
Well I did some poking around with the wiring. The whole compressor area, wires and all is absolutely covered in oil from years of leaking so I thought there might be enough moisture to cause a short circuit. But I checked the green wire that controls the clutch, from the connector, and it doesn't seem to be grounded. When the air con is switched on, the other side of the connector on this green wire goes to 14v.
The one thing I haven't been able to do is test continuity from this live wire down to the compressor, because I can't access the wire at the clutch end.
Anyone know how this wire connects to the clutch? Visibility is bad down there and I don't want to go removing stuff if it turns out there's no way to get at the wire.
The one thing I haven't been able to do is test continuity from this live wire down to the compressor, because I can't access the wire at the clutch end.
Anyone know how this wire connects to the clutch? Visibility is bad down there and I don't want to go removing stuff if it turns out there's no way to get at the wire.
05-20-2012, 12:41 PM
#12
AudiWorld Super User
BTW...it's highly unlikely you were able to charge it without the compressor running.
05-20-2012, 12:47 PM
#13
AudiWorld Super User
All AC clutch wires come out of the coil near the shaft end of the compressor. They physically have to.
Get to the serp belt/compressor clutch and you can see the wire coming out of the clutch coil. Supply 12v to that wire with a probe and/or probe for voltage...if you have voltage near the coil then the clutch is gone. The coil/clutch comes as an assembly and is pressed onto the compressor. Although you CAN change the clutch, if that compressor hasn't been run in a couple of years and was undercharged or discharged, chances are it's bad...once you go to the effort of getting at the compressor to take off and replace the clutch you might as well replace the compressor. On old cars you should also flush the system and replace the receiver/dryer.
On my old Saab 900Turbo I had to replace the HP and LP hoses..they came as an assembly with a manifold that bolted to the compressor and the other ends went to the receiver/dryer and the expansion valve/components.
Leak in HP hose fitting where hose went into crimp. Unfixable. Point is that hoses get old, I don't know what the estimated or replacement life of the HP hose is but if you're replacing the compressor take a good look at the HP hose.
Get to the serp belt/compressor clutch and you can see the wire coming out of the clutch coil. Supply 12v to that wire with a probe and/or probe for voltage...if you have voltage near the coil then the clutch is gone. The coil/clutch comes as an assembly and is pressed onto the compressor. Although you CAN change the clutch, if that compressor hasn't been run in a couple of years and was undercharged or discharged, chances are it's bad...once you go to the effort of getting at the compressor to take off and replace the clutch you might as well replace the compressor. On old cars you should also flush the system and replace the receiver/dryer.
On my old Saab 900Turbo I had to replace the HP and LP hoses..they came as an assembly with a manifold that bolted to the compressor and the other ends went to the receiver/dryer and the expansion valve/components.
Leak in HP hose fitting where hose went into crimp. Unfixable. Point is that hoses get old, I don't know what the estimated or replacement life of the HP hose is but if you're replacing the compressor take a good look at the HP hose.
05-20-2012, 01:42 PM
#14
OK I'll try to get better access and test the connection properly. I can see a wire going in behind the pulley into the clutch, but it's insulated of course so I'll have to dig around to see if I can access the conductor. Looks like I might have to put it into the service position.... 
If the clutch is indeed broken, or the compressor I probably won't remove it myself, I'll probably take it to a pro in that case.
Good point about not being able to charge it without the compressor running - I hadn't thought of that. I went by what it said on the gauge that came with the refill kit but it did say that the reading would only be accurate with the compressor running.
If the clutch is indeed broken, or the compressor I probably won't remove it myself, I'll probably take it to a pro in that case.
Good point about not being able to charge it without the compressor running - I hadn't thought of that. I went by what it said on the gauge that came with the refill kit but it did say that the reading would only be accurate with the compressor running.
06-28-2018, 05:10 PM
#15
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Audi Q5 air conditioning problem
My Audi Q5 2013 2.0 tdi,took it to get recharged with gas,it was full of gas so got mechanic to put computer on it,it’s bring up fault code “magnetic coupling circuit open short” so I replaced the compressor unit as a whole,I still can’t get air con to blow cold air,the clutch won’t engage when I turn air con on inside car,the clutch is engaging when I put power to it using probe,I also replaced pressure sensor and still have same code coming up on computer when I test it,can anyone help wat else can I check ? And does anyone e know were the relay for air con is?i also checked the fuse which isn’t blown either
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