87 M6 A/C QUESTION

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
emac
Posts: 142
Joined: Thu Feb 06, 2020 2:57 am
Location: SC

87 M6 A/C QUESTION

Post by emac »

Drove the M6 today and used the ac. The rear ac blew very cold, but the front was hit or miss. No matter where I dialed the front temo knob the ac just didnt get very cold in the front. Seemed to work better if I turned the rear temp up about half way. i am thinking the front temp controller knob isnt doing its job. Any thoughts? Seemed to work fine the last time I drove it. Thanks!
User avatar
cmcgettrick
Posts: 16
Joined: Sun Jul 03, 2022 2:47 pm
Location: Charleston, SC

Re: 87 M6 A/C QUESTION

Post by cmcgettrick »

Typically this is a sign that there is a leak in the system. If you had said the front was cold and the rear was warm then I would say the rear expansion valve is most likely the problem. Have someone check the system to be sure.
Chuck
1988 E24 M6
emac
Posts: 142
Joined: Thu Feb 06, 2020 2:57 am
Location: SC

Re: 87 M6 A/C QUESTION

Post by emac »

Thanks Chuck, that would make sense. The system has enough charge to run one but not both. I know the previous owner replaced something he called the suction throttle valve. He put a lot of effort into getting the AC right. May just be down on the charge a little.

ernest
TimU
Posts: 134
Joined: Tue Dec 14, 2021 2:16 am
Location: Sydney

Re: 87 M6 A/C QUESTION

Post by TimU »

This is a typical sign of a failed "Voltage Regulator" which controls the coolant flow between the front and rear evaporator coils.
The VR is located in the engine bay, part number 64511380659.
https://www.realoem.com/bmw/enUS/showpa ... 4511380659
04/1986 635csi Euro spec
Australian Delivered, RHD
Post Reply