A/C Compressor Clutch Problem ? - The Unofficial BMW M5 Messageboard (m5board.com)

dronfieldm · 9th September 2002, 13:49

My 1995 M5 had only done 1000 miles in the 18 months before I bought it. The AC gas had obviously escaped due to lack of use. I had the system professionaly charged and tested. All OK. 3 months have gone by, and the AC appears inoperative. I can hear no compressor engaging when I press the AC button, and the idle speed does not change/dip. (Button still lights up)

I previously (after the fix) had a problem when I couldn't turn the AC off (light off in switch but compressor still engaged).

This leads me to believe that the compressor "clutch" is now stuck off as oppose to stuck on. Is there an electrical feed for this I can test ? And I assume the "mechanism" is on the front of the compressor.

Any ideas as to how I can "free it". If I don't get it operating soon, the gas will eventually escape will it not ?

I am a little sceptical about taking it to a garage, as I'm pretty sure the problem is only "minor".

Any thoughts ?

Thanks
Mark

Alan Archer · 9th September 2002, 20:20

I HATE to post negative news

but from what you have described it sounds very possible
that the gas has already escaped again.

It's very likely that the "low pressure switch" ( a safety device
which prevents compressor damage if system pressure is too low)
has activated thus disabling the compressor.

Sadly, as you (beautiful i've no doubt) car has only done 1000miles (!) i think it's likely that the A/C hasn't been run
for 10 mins every month of the cars life.

Naturally check all fuses, take it back to the guy who gassed it,

but sadly, from experience...i think it's leaking again.

Regards,

Alan Archer.

Alan Archer · 9th September 2002, 20:23

However, if you check the wiring to the compressor&
disconnect it, you should be able to supply +12volts to
it & get it to engage.

DO THIS WITH THE ENGINE OFF OBVIOUSLY !!!

If it engages then test the feed is activating (with a
meter)
However, no feed could still indicate low system pressure.

Regards,

Alan Archer

dronfieldm · 10th September 2002, 11:10

Many thanks Alan. I'll speak to the air con people.

PS - My car has now covered 74,000 mls. It had only done 1000 mls in the last 18 months before I bought it. Sorry if I misled you !!!

All the best
Mark

g boyd · 11th September 2002, 09:19

Mark/everybody

The AC system must be run 5 to 10 min every week to circulate the oil and refrigerant, this will also slow down the build up of condensation which is the main reason why the components fail over time,

The evaporator went on my 92 M5 last year (I was told its the same part No as the 8 series) you would not believe the corrosion inside the old evaporator due to the condensation,

The good AC techs will have a sniffer tool which they place over the pipes etc to find the leaks,(good if the leak is big) also they can recharge the system and put a dye in so you can see the leak ( I prefer this one it takes more time but you know yourself were the leak is)

Graham