I have a 2007 SType R that I’ve owned since 2009.
A/C compressor just replaced by local Jaguar dealer under parts warranty from Oct 2020 replacement. When idling the compressor clutch is engaging/disengaging very often - more often at lower A/C temp setting - every 20 to 30 seconds. Can’t tell if happening when driving.
I had not noticed this previously in the last 12 years, but paying close attention after as the replacement only has 1 month warranty.
Is this normal for S Type A/C compressor clutch to engage and disengage frequently?

This is the 5th compressor since the car was new.
Thanks

 

Do you know if this latest compressor has had the modification to the internal pressure regulating valve?


http://www.jagrepair.com/images/TSB/...fficiently.pdf


If so, it may be normal for the clutch to cycle fairly often.

If not modified, this valve is designed to limit cycling, but it can reduce cooling capacity.

Five compressors, though? I wonder if the problem is being misdiagnosed. My ‘02 (340k miles) is still on the original compressor and it works great. Say the actual fault is a slow undiagnosed leak somewhere in the system. The system may work fine for three or four years until cooling drops off. A perfectly good compressor gets replaced and all seems good because this requires a full evacuation and recharge. The recharge masks the leak, until another three or four years go by…

 

More thoughts on a possible misdiagnosis. An unmodified compressor is designed to operate at reduced capacity under certain conditions. Most compressors have only full on and full off, but not this one.

If a mechanic was only accustomed to the full on/off type, he might think the variable output version was defective. In fact, continuous engagement with an on/off type is one indication of a tired compressor.

If the problem returns, I’d be tempted to try an independent AC specialist instead of the dealer. Ask if they are familiar with the Visteon variable output compressor. If not, keep looking elsewhere. Your wallet will thank you.

 

It would be helpful to hook up a set of gauges and see the pressures as it cycles. One of the switches may be defective. As Karl states the variable visteon is very reliable and 5 sounds like too many. Even an evacuation then a vacuum suck down with a good electric vac pump can show a lot. The trick to all this is knowing what the pressures mean and even the vac portion of how long it takes, vac achieved and does it hold vac for a while when the pump is shut off. I know this is a lot but you can arm yourself with knowledge and ask the questions of the tech. Again, as Karl states and i agree, throwing parts and money at these cars fishing for a cure will lighten the wallet significantly. Keep us posted

 

Thanks for all the great responses so quick.
yes I believe that the spring in the compressor was modified as the service advisor told me that they were now changing the spring in the back of the compressor and should get improved cooling - which it feels like it now has.
Also the old compressor seemed to stop cooling for a couple minutes if I was accelerating and went over 5000 rpm. Did not used to do this much in the past but had car dyno tuned with fresh air intake and cat back exhaust and computer programmed and now I can’t keep my foot out of it - so much more fun to drive 🤩

 

Yes the AC is shut off when you floor the gas pedal. Suppose to so you get maximum acceleration.
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