e12 based hvac question (fan control)
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e12 based hvac question (fan control)
for those with early cars. i recently swapped out transistors and the outer blower motor for new..
i noticed something ive not before on reassembly and testing.
the lower blower motor in the console is always on (low speed) when i key is on, even if the left : "heat - O - cool" dial is set to O.
is that correct ?
if i turn to warm it shuts off for the other.
i noticed something ive not before on reassembly and testing.
the lower blower motor in the console is always on (low speed) when i key is on, even if the left : "heat - O - cool" dial is set to O.
is that correct ?
if i turn to warm it shuts off for the other.
.1977 H&B 630CSI - http://www.sidedraftsix.com.
Re: e12 based hvac question (fan control)
It shouldn't. Sounds like it is still getting a current draw through that switch. What exactly did you replace?
Dale
Buffalo, NY
Dale
Buffalo, NY
1980 633CSi
1987 325is (sold)
2001 740iL Sport (sold)
2007 328xiT (Sold)
2014 320dT (Sold)
Current: 2023 Jetta GLI M/T
2007 GMC Sierra,
1972 Pontiac LeMans Sport Convertible
1987 325is (sold)
2001 740iL Sport (sold)
2007 328xiT (Sold)
2014 320dT (Sold)
Current: 2023 Jetta GLI M/T
2007 GMC Sierra,
1972 Pontiac LeMans Sport Convertible
Re: e12 based hvac question (fan control)
replaced both transistors and the heater blower..
seams as if when the dial is set to O the ac blower is running, only off when turned to hear
.1977 H&B 630CSI - http://www.sidedraftsix.com.
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Re: e12 based hvac question (fan control)
Carl I am having problems with the circuit board for my fan rheostat as we speak affecting fan speed being on and off. I have gone through all the spares I have and can't find a good one. It never ceases. Biggest problem I am having with mine is it wasn't factory air and we are putting all the controls for factory air in and have pulled all the after market things out. When I tore the car down many years ago, I pulled an after market loom for the add on A/C out that literally was balled up behind the glove compartment as big as a tennis ball. There was a rheostat of some sort in the glove compartment and I think that was what was used for the fan control. I never used the A/C as I tore the car down 3 days after I brought it home. At least after 10 years it is running and hopefully will be drivable by the end of summer. Again, we are 100% sure it is the circuit board as my problem.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
flickr.com/photos/bertsphotos.
Re: e12 based hvac question (fan control)
I'm rather sure that A/C blower does not work when temp.selector is on 0 or turned on red area. But I'll check carefully abd let you know when I got my car back from garage.
Once I found on this forum A/C wiring diagram for '79 model - see attached. Maybe there's some plug mistake and specialist will find the problem having diagram. Good luck.
Once I found on this forum A/C wiring diagram for '79 model - see attached. Maybe there's some plug mistake and specialist will find the problem having diagram. Good luck.
- Attachments
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- Air Conditioner 1979-LHD & RHD-#01.JPG (868.45 KiB) Viewed 8119 times
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- Air Conditioner 1979-LHD & RHD-#02.JPG (280.64 KiB) Viewed 8119 times
1980 635 CSi EU
M90/L-Jetronic/manual
M90/L-Jetronic/manual
Re: e12 based hvac question (fan control)
janusz200 wrote: ↑Tue Mar 19, 2019 8:57 am I'm rather sure that A/C blower does not work when temp.selector is on 0 or turned on red area. But I'll check carefully abd let you know when I got my car back from garage.
Once I found on this forum A/C wiring diagram for '79 model - see attached. Maybe there's some plug mistake and specialist will find the problem having diagram. Good luck.
thanks please do!
i could be as simple as miss plugged wire when i reassembled. but honestly ive not got enough seat time prior to know if the AC Blower would blow when on "O". i would assume not.
.1977 H&B 630CSI - http://www.sidedraftsix.com.
Re: e12 based hvac question (fan control)
The AC blower should only work when the temp knob is turned from the 0 (0 will still run the heater blower but the heater valve is still closed) to cold/kalt. You should hear the microswitch click. There are two cams on the back of the temp switch. One controls the AC thermostat and the other the microswitch for the blowers.
Re: e12 based hvac question (fan control)
perhaps mine is backwards. ?wkohler wrote: ↑Wed Mar 20, 2019 5:02 am The AC blower should only work when the temp knob is turned from the 0 (0 will still run the heater blower but the heater valve is still closed) to cold/kalt. You should hear the microswitch click. There are two cams on the back of the temp switch. One controls the AC thermostat and the other the microswitch for the blowers.
.1977 H&B 630CSI - http://www.sidedraftsix.com.
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Re: e12 based hvac question (fan control)
Carl, the microswitch is item No. 25 in the diagram above
IIRC, this switch just completes the ground circuits to either the heater or A/C blower, interesting setup
From what I also recall, neither blower should be actually "blowing" air unless the rotary fan speed dial is turned
HTH
IIRC, this switch just completes the ground circuits to either the heater or A/C blower, interesting setup
From what I also recall, neither blower should be actually "blowing" air unless the rotary fan speed dial is turned
HTH
Bobbo
1980 633 CSi Cypress Green/Pearl Beige
2017 X5 M Sport Xdrive 35i Carbon Black/Ivory White
2005 330 Ci ZHP Cabrio Imola Red/Bone/Black
Re: e12 based hvac question (fan control)
https://imgur.com/H5hI4LC
Hi guys, I cant comment on the diagnosis, but this is the diagram from the BMW north america electrical troubleshooting manual. For a 1977 630. Hope this helps.
-Not sure how to embed the photo :S
Re: e12 based hvac question (fan control)
I've checked - A/C blower does not work with selector on 0
1980 635 CSi EU
M90/L-Jetronic/manual
M90/L-Jetronic/manual
Re: e12 based hvac question (fan control)
I am trouble shooting my HVAC system, and did a complete teardown and cleaned out the core. The main issue I have is that the whole system is dead. No ac or heater fan. Looking at the diagrams I will check the relays first as the fan speed control switch feels good, if the relays are good I will check the switch.
Am I on the right track?
Am I on the right track?
81 BMW 635csi RHD Euro manual.
02 M5
02 MCoupe
02 M5
02 MCoupe
Re: e12 based hvac question (fan control)
So the relays are all functioning correctly and the fan speed control switch is all good. Before I started strippping I checked there was potential accorss the fan fuse in the fuse box. I am now at a bit of a loose end...biggles wrote: ↑Mon Apr 20, 2020 2:36 pm I am trouble shooting my HVAC system, and did a complete teardown and cleaned out the core. The main issue I have is that the whole system is dead. No ac or heater fan. Looking at the diagrams I will check the relays first as the fan speed control switch feels good, if the relays are good I will check the switch.
Am I on the right track?
81 BMW 635csi RHD Euro manual.
02 M5
02 MCoupe
02 M5
02 MCoupe