ac clutch wiring
#1
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The ac clutch won't engage, I have tested the clutch with 12v battery and it is operating. I have power to the relay base and the fuse in the dash is good. Even when I select manual and ac on the dash control panel, the clutch does not come on. I have tried to add freon with my gauges and it accepted some, but the high side reading stays at zero. I have tried following the electric schematics but I lack full knowledge in this area. Any ideas of what I can do? It seems to me that whatever closes the circuit in the relay to send power to the clutch is not working.
Thanks, John
Thanks, John
#2
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Would be helpful to know your vehicle year and engine. Most V12 have the Harrison A6 compressor; earlier versions have a fusible connection at the compressor clutch, and later versions have the clutch grounded through the HSLP (high side low pressure) switch on the rear of the compressor- this prevents clutch engagement if pressure in system is below about 25 psi.
Common that if the system has been converted to R134a that the Schrader valves are so deep that your gauge connectors cannot push the stem to allow pressure readings or charging. Usually you can charge by weight through the low side port only, stable 25-30 psi with the compressor engaged at 75f would be close to a full charge. High side usually will be 150-200.
Common that if the system has been converted to R134a that the Schrader valves are so deep that your gauge connectors cannot push the stem to allow pressure readings or charging. Usually you can charge by weight through the low side port only, stable 25-30 psi with the compressor engaged at 75f would be close to a full charge. High side usually will be 150-200.
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ptjs1 (Yesterday)
#3
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it is a 94 xjs 2+2 with the 4.0 straight 6 and it is 134a. The schrader valves are fine, as I have had the gauges on and off them before. This problem abruptly occured with it going from blowing really cold ac to just blowing hot air. So I changed the expansion valve, which brings it to where it is now
John
John
#4
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To "trigger" the compressor relay needs "+" voltage from the climate control ECU and a ground. The ground comes via the pressure switch.
The diagram shows a "dual pressure cutout switch". My guess is that it breaks the ground path if pressure goes higher than xxx-value or lower than yyy-value
Cheers
DD
The diagram shows a "dual pressure cutout switch". My guess is that it breaks the ground path if pressure goes higher than xxx-value or lower than yyy-value
Cheers
DD
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ptjs1 (Yesterday)
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Jon
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ptjs1 (Yesterday)
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Yes
Item #3 in this illustration, located as mentioned on the AC pipe
https://parts.jaguarlandroverclassic...uMTkwNTk4NzAz/
Cheers
DD
#10
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I removed the ac clutch relay and with the engine running I put a jumper wire from pin 30 slot to pin 87 slot in the relay base. The ac clutch engaged so the compressor was turning, but still no pressure or freon flow. So I can only conclude the compressor is bad and that the ac pressure sensor/ switch is working as intended.
John
John
#11
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No change at all on your gauges?
I hope the compressor didn't grenade and throw junk thru your entire system.
As long as there is about 27-30 psi of refrigerant in the system, car not running, the switch should close and operate the clutch relay. The compressor does not need to be running for the switch to close. Maybe you have two issues.
Jon
I hope the compressor didn't grenade and throw junk thru your entire system.
As long as there is about 27-30 psi of refrigerant in the system, car not running, the switch should close and operate the clutch relay. The compressor does not need to be running for the switch to close. Maybe you have two issues.
Jon
#12
#13
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Jon
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Greg in France (Yesterday)
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