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A/C not turning on

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Danny Wilde
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Location: Italy

A/C not turning on

Post by Danny Wilde » Tue Jul 25, 2017 10:06 pm

Hi guys! :D It started as an intermittent issue, air con not starting and light not turning on on switch, once it did start the system worked ok.
Lately it has completely stopped turning on.

And even if I do not press the air con switch, if I open the middle slider it produces no air, if I turn the right intensity knob I can hear it turning at max but no air comes through :cry:

So I checked and cleaned the fuse, then ordered a new blower select relay (61361388911) from BMW and replaced it… no luck.

Image

Then I took the switch out, opened it and cleaned all of the connections which, as a matter of fact, didn't seem in a bad shape, just a couple on the outside were a bit "darkened" (see pic). Also replaced the old grease of the mechanism with new grease, popped it in again and…. still no luck :-k

Image

also removed the HVAC panel and cleaned the middle slider's sliding contact… no luck again..

Image


Does anyone have a clue?

Thanks for you help guys :-)
Danny
Last edited by Danny Wilde on Thu Jul 27, 2017 2:48 pm, edited 2 times in total.
9/1986 euro 635CSi manual Diamantschwarz

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Danny Wilde
Posts: 78
Joined: Wed Apr 18, 2012 8:44 pm
Location: Italy

Re: A/C not turning on

Post by Danny Wilde » Tue Aug 08, 2017 11:11 pm

Hi guys, now I'm trying to jump the connector of the middle slider hoping that that's causing the A/C problem, but unfortunately the colour coding and number of the wires on my car do not match the 1986 ETM manual.
Do you think I just should follow the wire color in my car and jump GN/BU and GN/BR together, or should I follow the number in the ETM and ignore the colour coding? (see pic below)

1986 ETM manual:

1 GN/BR
2 GN/BU
3 ground


MY CAR:

1 GN/BU
2 ground
3 GN/BR

Image
9/1986 euro 635CSi manual Diamantschwarz

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Danny Wilde
Posts: 78
Joined: Wed Apr 18, 2012 8:44 pm
Location: Italy

Re: A/C not turning on

Post by Danny Wilde » Wed Aug 09, 2017 7:32 pm

Hi guys, sorry to bump :oops:, but I really can't figure out which two wires I should jump in the outside air sliding potentiometer (the central slider on the HVAC panel).
As you can see in the post above, there is a mismatch in number and wire color between my 6 and the BMW ETM for 1986, if I make some random jumping attempts is there any risk of damaging something on the circuit?
I also just bought a tester, is there a way to determine which of the three is ground with it?

I apologize but I'm a real newbie with electrical stuff :mrgreen:
9/1986 euro 635CSi manual Diamantschwarz

baders
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Re: A/C not turning on

Post by baders » Wed Aug 09, 2017 11:43 pm

Danny. It is a potentiometer so you can test it with a multimeter. Unfortunately the BMW diagram does not represent the pot properly but you should still be able to test. One leg is voltage in (12v?), one leg is ground, and the third is the wiper output to the control unit.
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement

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Danny Wilde
Posts: 78
Joined: Wed Apr 18, 2012 8:44 pm
Location: Italy

Re: A/C not turning on

Post by Danny Wilde » Thu Aug 10, 2017 6:53 am

baders wrote:Danny. It is a potentiometer so you can test it with a multimeter. Unfortunately the BMW diagram does not represent the pot properly but you should still be able to test. One leg is voltage in (12v?), one leg is ground, and the third is the wiper output to the control unit.
Thanks Baders, wow I really like Arktis Blau :D . I checked on the internet on how to test a potentiometer, but this is the connector to the potentiometer that I need to jump in order to bypass the potentiometer itself, do you know how I should be able to determine which is ground of the three? I guess I should jump the remaining two right?
Should I set the tester to V (DC) and try connecting two at a time? real newbie here :mrgreen: ..
9/1986 euro 635CSi manual Diamantschwarz

baders
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Re: A/C not turning on

Post by baders » Fri Aug 11, 2017 2:44 am

Danny Wilde wrote:
baders wrote:Danny. It is a potentiometer so you can test it with a multimeter. Unfortunately the BMW diagram does not represent the pot properly but you should still be able to test. One leg is voltage in (12v?), one leg is ground, and the third is the wiper output to the control unit.
Thanks Baders, wow I really like Arktis Blau :D . I checked on the internet on how to test a potentiometer, but this is the connector to the potentiometer that I need to jump in order to bypass the potentiometer itself, do you know how I should be able to determine which is ground of the three? I guess I should jump the remaining two right?
Should I set the tester to V (DC) and try connecting two at a time? real newbie here :mrgreen: ..
Ground is easy to find with your meter set to ohms. One leg on any known ground, one on the brown. That will confirm ground. The thing that is difficult is what will happen when you bridge "voltage in" to the wiper (voltage out). Not sure exactly how this potentiometer is supposed to work inputting to the control unit.
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement

User avatar
Danny Wilde
Posts: 78
Joined: Wed Apr 18, 2012 8:44 pm
Location: Italy

Re: A/C not turning on

Post by Danny Wilde » Fri Aug 11, 2017 6:06 am

Thanks for your precious help Baders! :D
So I finally determined which is which, I also made a (risky) attempt at jumping together the two that are not ground in an attempt to bypass the middle slider (outside air), but unfortunately the A/C still doesn't come on (no light on switch) :(, already checked fuse, replaced relay, and opened and cleaned the inside contacts of the A/C switch, which looked quite ok by the way….
At the beginning of the issue, it started working intermittently and it looked like an electrical issue since while working the system was flawless (had just recharged with R12), when not working both the A/C and middle slider (outside air) were totally dead… Now it's been solid dead for quite a while.

Any idea on which could be the next test? :?:
thanks
D
9/1986 euro 635CSi manual Diamantschwarz

baders
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Re: A/C not turning on

Post by baders » Fri Aug 11, 2017 8:07 am

Danny, this is now a hard fault so we should be able to find it :)

Time to work methodically through with your multi-meter and the ETM.

Is the A/C selector switch passing power ? Check for voltage to ground either side.
Is the compressor clutch coming in ? If so then the A/C selector switch is passing power.
Are the A/C and heater blowers actually pushing air ? (When heat/cool selected).
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement

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