C5 X7 Aircon Compressor not engaging

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lorddevereux
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C5 X7 Aircon Compressor not engaging

Post by lorddevereux »

I have a fault with the aircon in my 2010 X7 3.0 HDi - in that the button lights up happily but the compressor doesn't engage.

I've checked the cooling fans on an actuator test and they both run perfectly. I've also checked the compressor engagement and that test completes successfully (without error). I can't hear an obvious click, although I'm not sure I ever did on this car when it was working ok and there's a fair bit of ambient noise around here.

The air con pressure is showing as 5.6bar (I don't know if that's good or bad?). When aircon is activated, the "status" in the Engine ECU live data changes from "No aircon request" to "Air condition request: Authorisation refused by engine ECU".

Can anyone shine a light on what the pressure ought to be showing, and whether it might be refusing to engage because of low pressure? If that's a workable value, I'll have to look deeper into the compressor clutch.

Thanks!

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GiveMeABreak
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Re: C5 X7 Aircon Compressor not engaging

Post by GiveMeABreak »

If the gas is low the compressor will be automatically shut off to prevent damage. You'll probably need a top up or if you have recently, then you may have a leak. Most common is the condenser radiator at the front that gets 'stone chipped'.

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GiveMeABreak
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Re: C5 X7 Aircon Compressor not engaging

Post by GiveMeABreak »

There is low and high pressure to be checked with engine stationary and engine running.

If the High pressure (at 20℃) is lower than 6 BAR or lower than 7 BAR at 25℃ and the Low pressure is lower than 2.4 BAR then you have a lack of refrigerant.

lorddevereux
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Re: C5 X7 Aircon Compressor not engaging

Post by lorddevereux »

Thanks Marc! The value I have is from engine ECU live data, reading 5.6bar with engine running at idle and it's just labelled "Air conditioning circuit pressure".

I just don't want to go get a regas and then find the compressor clutch is knackered and have to get it done all over again!

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GiveMeABreak
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Re: C5 X7 Aircon Compressor not engaging

Post by GiveMeABreak »

That's the same problem I have with our other C3, except that ATS re-gassed it last year and it is running warm now - so I suspect a leak and the only way to find that is getting dye in for investigation....

Cit fan 151
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Re: C5 X7 Aircon Compressor not engaging

Post by Cit fan 151 »

It was the clutch that failed in our 3.0 HDI C5, but I am not sure whether it is the same problem in your car? viewtopic.php?t=67103

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xantia_v6
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Re: C5 X7 Aircon Compressor not engaging

Post by xantia_v6 »

lorddevereux wrote:
23 Apr 2021, 11:54
Thanks Marc! The value I have is from engine ECU live data, reading 5.6bar with engine running at idle and it's just labelled "Air conditioning circuit pressure".

I just don't want to go get a regas and then find the compressor clutch is knackered and have to get it done all over again!
5.6 bar should be plenty of refrigerant. If you have access to diagbox, you should be able to see if the compressor clutch is being activated, and if not, there should be a fault code or sensor state that is disabling it. Also check the engine ECU fault codes, as some will disable the a/c compressor.

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GiveMeABreak
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Re: C5 X7 Aircon Compressor not engaging

Post by GiveMeABreak »

I already checked the specs Mike and officially if under the pressures I stated - that is the diagnosis.

lorddevereux
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Re: C5 X7 Aircon Compressor not engaging

Post by lorddevereux »

Cit fan 151 wrote:
23 Apr 2021, 22:45
It was the clutch that failed in our 3.0 HDI C5, but I am not sure whether it is the same problem in your car? viewtopic.php?t=67103

Thanks! It's looking like it is the clutch as I'm pretty sure there's no click from the actuator test at all. Looks like it may be possible to unbolt with the compressor still attached (i.e without requiring the hoses disconnected?)

Cit fan 151
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Re: C5 X7 Aircon Compressor not engaging

Post by Cit fan 151 »

The diagnosis for our C5 was a Clutch Control Fault - C994. The dealer wanted to replace compressor, condenser and regass.

As I was unsure whether the clutch could be separated from compressor on our model (not sold separately by dealer), I ended up buying a 'remanufactured' compressor. The mechanic simply swapped the clutch from the 'remanufactured' compressor to the one on the car and hence no regassing was required. That was a few months ago and it has been fine since.

I have since done some research on obtaining the clutch only, so I can attach it to my spare compressor (if necessary). It is important to identify which Sanden compressor you have on your car - I understand this information is available from Servicebox for a nominal fee?

I was advised by the supplier of the following clutch that it was the right one, based on the compressor details I provided for our car https://www.aliexpress.com/item/1005002297371884.html I am not able to confirm it is the correct one, or what the quality of it is, but it certainly is much cheaper (and environmentally friendly) than the original solution I was offered for a failed AC clutch!