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muddycharles
09-24-2024, 04:40 PM
Hi Guys,

I have been enjoying driving the car but am being bedeviled by the AC (automatic control)

Checked pressure on system (was low - now at 33Lbs)

AC cold most of the time. Yesterday I drove to work (Miami) for 20 miles in the heat and nice and cool. Parked in a Garage and when I came home no AC (light was on, and air blowing). Had to turn off and on several times, and got it to work about 3/4 of the way home. Nice and cold air after that.

This has happened a few times - and there is no consistency to why it's working or not working.

Any suggestions to trouble shooting steps? I was on the highway so could not stop to check Aux Fan and if it was blowing.

Thoughts I have
1) Change the two aux fan relays
2) ?
3) ?

Thank you!

Ive read the AC ECU can fail, but the comments seem to point to flickering displays or the AC turning on and off. Im not seeing any of that.
Braymond141
09-24-2024, 04:55 PM
That is the classic sign of non functioning aux fan. Either the fuse is popped or the fan is dying or the rad temp switch is bad.
muddycharles
09-24-2024, 05:06 PM
OK - so not the relay then. I'll start with the fuse. Then check fan function with car at idle and ac on / off
scooper
09-24-2024, 11:13 PM
33 lbs seems very low especially if you live in Miami. If so, there may be a leak somewhere. But check out the aux fan too.
muddycharles
09-29-2024, 02:00 PM
Brett - Well - the 5A fuse had popped. Replaced and we are running. There are two relays - a yellow one and a violet one. Should I replace those too?

One strange thing - on one site it mentioned relay 61361391397 as the correct one, but the actual one is the violet one 61361388911

Not sure anymore with the different references, but the high speed relay should be the violet one? (thats the one that is in there now)
muddycharles
09-29-2024, 02:23 PM
Wait! There are two related fuses. One is a 30AMP fuse and one it a 5 AMP fuse. It was the 5AMP that blew - you upped that to 20AMPS? Fuse #16 is the one Im referring to (the other one that is OK is fuse 41- that one is oK)
Braymond141
09-30-2024, 01:01 AM
No, disregard. I erased my reply.
muddycharles
09-30-2024, 09:06 AM
OK - you had me worried there.
muddycharles
10-02-2024, 06:58 PM
sigh - worked in the AM to work and not in the PM home. Back to square one
scooper
10-06-2024, 04:12 PM
what are the readings for low and high pressure? I think the problem might be electrical though.
M3C
10-13-2024, 01:20 PM
It depends on ambient temperature, this is general guide and do not think it varies much for BMW vs. other car brands.
https://rechargeac.com/how-to/ac-system-pressure-chart/

Did you check the low/high pressure with AC gauge kit?
muddycharles
10-14-2024, 04:06 PM
I have the kit on order - should arrive this week. will post the readings.
RobertFontaine
10-15-2024, 09:16 PM
Silly question but have you checked the pulley clutch?
They do tend to wear out.
muddycharles
10-16-2024, 09:52 AM
Robert, The kit for the AC arrives tomorrow so I will test that. However I did have an experience the other day where the AC worked, and I went over a bump on the highway that was not small - the AC cut out for about 5 secs (humid air came in) - then it came back. Not sure if a pulley can contribute to this

How do I check
RobertFontaine
10-16-2024, 02:24 PM
The AC pulley clutch connects and disconnects the pulley from the ac pump.

https://www.youtube.com/watch?v=RlN__l4arOs