Dead AC

pmansson

pmansson

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switzerland and sweden
Fairly new compressor. Always works, but today nothing happens as I turn the lower knob.
The fuse, 7? Which shares the left door window must be ok, as the window funs normally.
Is there another fuse, or relay that I should check?
Thanks,
Peder
 
There is a relay, usually below the ignition coil, so check that. Does your condenser fan come on? There is a fuse for that, find the relay and trace the 30 wire back towards the condenser from the relay and it should show up somewhere. Depends on how it's all wired. Your fan in the interior still works, just no compressor kicks on?
 
Windows and A/C do not share a fuse on my 73. I would check power at the relay under the coil. If compressor and compressor fan don’t turn on you aren’t getting power to the relay which only starts that fan, not the compressor. On my coupe the temp sensor that goes into the evaporator box would occasionally touch the squirrel cage motor and blow the fuse. On on your A/C console, the fan should always turn on first, then turning on the temp switch sends power to the relay. If no console fan it must be a fuse.
 
Thanks
This afternoon it worked as normsl, again. Strnge and not entirely satisfying as I did nothing between the morning drive, and this afternoon
 
A few pictures...
 

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Very cool engine.
3,0 L, over square with 3,5 block and 2,5 crank. 339 HP and 422 Nm. Revs up tp 9800. Great sound!
 

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pmansson said:
Fairly new compressor. Always works, but today nothing happens as I turn the lower knob.
The fuse, 7? Which shares the left door window must be ok, as the window funs normally.
Is there another fuse, or relay that I should check?
Thanks,
Peder
Click to expand...
Peder,

The switch in the console has a tendency to go bad. I had that issue with my '74 last summer. Many times it would work, sometimes not. It usually functioned when I turned it on and the system was cold. If I drove for a while, then turned that switch or the car off, when started it would not function.

At last report, there was ONE new BMW switch available in the US. May be several available in Europe. Your switch might be repairable, I think there is a post somewhere on the forum about the repair of a '74 switch.

Beautiful cars.

Good luck
 
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The Murray Climate Control switch from O’Reilly looks like a winner. The BMW knob fits right on as does the hold down fastener with the split ring pliers holes. Too bad it’s not the whole problem with my car, there’s no power to the AC fan switch below!
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On the bench it turns very stiff and the VOM says it’s either off or on whereas I was expecting a rheostat function, perhaps that is modified by input from the sensor when installed?

Will report back when it’s all back together, right now I think there’s supposed to be switched power at the brown-green wire at the lower switch and there is not. There’s a good wiring diagram posted here but without the accompanying legend I am struggling so I have the repro blue books on order.
 
The wiring diagrams I posted have pdf legends with them.

Wiring diagram - late '73 - '75 e9's

I have searched several times for a wiring diagram of our e9's that were built late in '73 through '75 (I have a '74). There are quite a few changes made to these cars, but one specific and easy to spot one is the wiring/mountings for the window motors. The late cars used 2 wire connections...
www.e9coupe.com www.e9coupe.com
 
HB Chris said:
The wiring diagrams I posted have pdf legends with them.

Wiring diagram - late '73 - '75 e9's

I have searched several times for a wiring diagram of our e9's that were built late in '73 through '75 (I have a '74). There are quite a few changes made to these cars, but one specific and easy to spot one is the wiring/mountings for the window motors. The late cars used 2 wire connections...
www.e9coupe.com www.e9coupe.com
Click to expand...
Hi HB Chris, in that thread I see 74 Wiring Diagram legend but doesn’t include AC, and later in the thread another member posted the Comfort Eqpt diagram but no accompanying legend.
 
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