I installed a new compressor on my '01 S-Type and now the clutch won't come on. There is no signal to trip the clutch relay. Did I somehow kill the controller? Does the system know I don't have a genuine Jaguar compressor?

I charged the system and everything except the clutch relay is working properly. Do I need a contorller or what?

 

On the xk8, there is a specific fuse for the clutch compressor. Make sure you don't have one, and it isn't toast. Ours is only a 10amp.

 

Thanks for the suggestion. There is a fuse but it's good. The relay is getting power (and is good too) but won't engage because there is no signal from the Powertrain Control Module. Hard to believe I somehow blew the Control Module but it does not send the signal to the relay for some reason.

 

Look at the workshop manual's electrical guide for your specific year & engine size car. Generally there's a high-low (aka dual) pressure switch so if either is correctly or falsely triggering (use a meter to find out) the PCM will not command the clutch on.

There may be other interlocks also (such as an icing up switch).

And there's one or more relays so either check or swap them, too.

 

There is a pressure transducer. Seems it is working correctly as the cooling fan comes on in response to high side pressure rise. Good idea though, I'll investigate the transducer.

Thinking that it is not likely other sensors bad from me changing the compressor as the system was working before I removed the compressor. Was hoping for the "magic bullet" but I guess I'm into chasing the inputs to the Control Modules.

Thanks for the response.

 

How can you have high side pressure rise if the compressor clutch does not operate? If the pressure rises, the clutch must be operating, surely?

 

"Fixed" Headed back to jack with the pressure sensor and the clutch came in. Apparantly needed time to reset or one more cold start.

Response to V8: Once I diagnosed the relay trigger from the PCM as the fault, I jumpped the relay to charge the system. Noted during charging that all good excepth relay trip.

Thanks for your help guys!

 

If it's working - hooray!