A/C button should light regardless of charge??

[Derek A.]

I know when I did my car (90 535i) the aux fan came on and the dash button lit up green - when the air was turned on. The compressor didn't cycle until the low side pressure came up.

My friend has a 91 m50 525i and his system does not seem to be powering up. I have had him check the connections at the compressor and the fuse. Any other ideas on what to check to make sure the a/c system is at least powering up ?

[granit_silber]

I know when I did my car (90 535i) the aux fan came on and the dash button lit up green - when the air was turned on. The compressor didn't cycle until the low side pressure came up.

My friend has a 91 m50 525i and his system does not seem to be powering up. I have had him check the connections at the compressor and the fuse. Any other ideas on what to check to make sure the a/c system is at least powering up ?

Derek,

If the system pressure isn't high enough (i.e. a leak in the system) the compressor doesn't engage even if the light's on. It's a failsafe so the compressor doen't destroy itself if there's nothing to compress. So he probably has a leak or low charge.
-ashley

[Derek A.]

Derek,

If the system pressure isn't high enough (i.e. a leak in the system) the compressor doesn't engage even if the light's on. It's a failsafe so the compressor doen't destroy itself if there's nothing to compress. So he probably has a leak or low charge.
-ashley

His dash light is not coming on - so the thought is something electrical is the #1 item to troubleshoot. We don't know the state of the system charge. Fuse looks good. Is there a relay to look at? switch problem?

[cableface]

His dash light is not coming on - so the thought is something electrical is the #1 item to troubleshoot. We don't know the state of the system charge. Fuse looks good. Is there a relay to look at? switch problem?

My light was coming on only sometimes on my 525. Fuses and everything were okay. It turned out to be the button/switch itself. I bought the whole dashboard control board on ebay for 20 bucks and it works great now.

[Bellicose Right Winger]

I struggled with this in my E34's until I looked at the ETM. The AC on M30 and M50 E34's are wired differently. The M30 will light the AC button but won't allow compressor to start if charge is low. The M50 will not light the AC button if charge is low.

Paul Shovestul

I know when I did my car (90 535i) the aux fan came on and the dash button lit up green - when the air was turned on. The compressor didn't cycle until the low side pressure came up.

My friend has a 91 m50 525i and his system does not seem to be powering up. I have had him check the connections at the compressor and the fuse. Any other ideas on what to check to make sure the a/c system is at least powering up ?

[PeterInSTL]

I have a '91 525 and last summer when I went to use the A/C for the first time the Snowflake Light woul not illuminate. It turned out to be that I had leak in the system, and I later confirmed that if the system is not charged the light will not illuminate. So with that said I reiterate and say check system for charge.