phillygoat

Started up the car after work today and put on the AC. Within seconds the ole chirpety chirp started, i left it for bout 30 secs or so then turned it off. Got in the car bout 2 mins later and drove off. Got on the motorway and turned on the AC, nothing. However it came on bout 10 mins after running, with the occasional chirp. I need AC in southern Spain, what gwaan with my beast? just paid €640 for a full BMW stealership service aswell, the wallet can´t be doing with repairs just yet.

farrell

Hello
If your a/c was properly refilled very recently, then the vehicle should be returned to the dealer.
Did you ask them to check & fill the a/c system ?

All aircon tasks are generally not considered part of the inspection service apart from operation check by the technician to note weather face vent temp reduces with operation.
The fact that you hear the clutch engage the a/c compressor & the cooling strategy run the electric cooling fan as part of this is a dead giveaway to operation.

General good practice is to purge the system of gas (R134a) oil, & continue the vacuum draw to remove water moisture from the system that the reciever drier has not captured.
Once this has been done the system is pressure checked via a leakdown check with a careful eye on the pressure gauge.
If the system holds pressure for half an hour, its safe to recharge with gas & oil.
If it does not hold pressure, then you then proceeed to add a dye to the charge port & circulate at operating pressure to see where the vent to atmosphere is occuring.

When you consider the charge capacity of 1650gms of oil & gas, its a large
system capacity double the size of many vehcles & very costly to charge without a leakdown check.
The gas venting is a environemental issue also, hence the recovery system method used to draw off whats in the system to start with.

Bottom line.
The system is either over pressurised & the trinary ( pressure) switch is cutting the compressor ( rare )
The system pressure has dropped below safe operating pressure due to leak in the system & the trinary switch has cut the compressor op to safe the system from further stress.

Cheers
Farrell

nebpor

Can I butt in here and ask if the aircon is common to all 5-series and isn't specific for the M?

Mines has been broken since last summer and the car isn't going near a dealer - it appears the compressor has given up... I do have a friend with a breakers yard though, so if it's a common part I can get him to keep an eye out for me!

thanks ...

Alan Archer

The general system is generic across the E34 range but
the pipework / compressor mounting will be specific to the S38 motor
installation.
However it may be possible to use a suitable compressor from a donor
E34, although most of those for sale on Ebay are from later M40 engines
with the wrong pulley arrangement.

Condensors / Evapourators should be a common fit.

If the lamp illuminates in the A/C switch when you turn it on, the system
has minimum pressure and should blow at least SOME cold air.
If the lamp doesn't come on then the low pressure switch has activated
to protect the compressor as Farrell stated.

If you get a "chirp" from the compressor then perhaps it has siezed...
or if you are lucky its just poor belt tension !

Regards,


Alan.

__________________
///M5 the only substitute for capacity is even greater capacity...

nebpor

Thanks Alan