E30 - AC light is off and no air

qdessa · 07-05-2008, 01:41 PM

All,
Driving along happily with the air blowing cold and the system quit. The blower works in all speeds, but when the switch is depressed there isn't a light and there isn't any cold air.

The low pressure switch is closed ( 0 ohm across the switch )

Any ideas?

Thanks
Alan

Yurick · 07-05-2008, 05:48 PM

Did you check all the related fuses?

qdessa · 07-07-2008, 06:38 AM

Checked fuse #20 - it is good.

Another detail - I push in the switch and the fan comes ( fan switch is in the off position) but the compressor does not.

skoobeesnak · 07-07-2008, 12:35 PM

I had the same problem and I am fairly sure I know what you need to do to fix it. You will have to take apart your dash by removing the radio, and the panels that hold them on. Once you have done that behind the slider controls there are two wires that connect to a circuit board that is just behind but built into the slider controls. This board sometimes fries and then doesn't allow the AC to turn on. Mine were half burned and it was easy to see that they were bad. The solution is just to cut them back strip the wires and twist or solder them together, tape it up and you should be good to go.

qdessa · 07-10-2008, 09:19 AM

OK - the problem has been located. As skoobeesnak suggested I checked behind the slider controls. What I found was that a trace ( more like track ) had burned off the board. This board 'senses' the position of the slider switches so the AC won't work if the center slider isn't all the way to the right.

Jumping the connector allowed the AC compressor to kick on. The only issue now is that the wires are getting very hot. A little more investigation is required.

Thanks for the help!

qdessa · 07-13-2008, 04:46 PM

the saga continues - there is a reason for the trace to burn off, after jumping the connector the wire gets so hot it starts to smoke. Putting the fan on high blows the 30@ fuse. ( the fan on high without the AC is OK).

If I take the compressor out of the circuit there isn't a problem - the wire stays cool, etc. So that leads me to believe there is something wrong with the compressor. The compressor wire to ground is around 3 ohms. Is that normal? Is the diode shot?

Thanks for any help!

coolbear1 · 07-15-2008, 07:28 PM

Have you tried to jump directly to the compressor and take an amp draw reading with an amp meter?
If you do, you might consider putting a 30a fuse in the jumper in case the compressor clutch winding is faulty. If it blows it will tell you where the fault is, and it will keep your jumper from becoming a welding rod.

skoobeesnak · 07-25-2008, 05:39 AM

Just to give you an update. Mine would kick on as well but blow the fuse after a while or if I turned it up to fan speed 3 it would blow immediately. So I ended up going to a salvage yard and getting a new connector that connects to the slider controls since mine was half melted and bought a new slider control board from the BMW dealer for around $75. Replaced the whole deal which was a bit of a PITA with the cables and clips it might be a good idea to get a few extra since I have lost one and still have yet to find it. Now it turns on no problem and I can run the fan at any speed. I would guess you will have to do the same thing, but you may be able to save some money getting the controls from the salvage yard.

Now I just need to figure out if I have a leak and acquire some R12 to refill it.

Good luck