heater blower inop any e12 guys on here that could help?

[bavarian]

need HElp , im getting no power to the ac heater blower ive traced it to the wires coming into the heater control panel , the heater control panel switches were cleaned and they arent getting any power , these wires go under the dash pretty deep and im having trouble finding where they go in order to further test, this is for the heater blower not the ac , fuse is good and have the correct fuse , blower motor is brand new bench tested , its just not getting voltage, any help is apreciated!!

 

[TomHom]

Hi,
giving the year of production would be helpful. I have the manual for August '73 onwards. I see that the speed regulator is the circular type integrated in the clock.
Whereas early versions may have the slider as in our E9?
So, which regulator is installed?
How far can you trace the 12V, up to the regulator?
You may try (if you know what you are doing) disconnecting one core running from the speed regulator to the fan and apply 12V directly. But be careful, avoid short-circuits!
- blue core 91 full speed
- black core 92 medium speed
- yellow core 93 low speed
This would tell you where to search next, either motor or regulator.
Did you ever noticed the fan motor in operation or is it a car you just started working on? A little bit more background information is always helpful!!
Thomas

 

[bavarian]

hey so its 1979 bmw 528 i and i just tested with power at the fuse everything works great including the fan speed switch i just cleaned, so now the question is why no power at the fuse , thanks for the help by the way

 

[bavbob]

I will be watching this thread as my e24 has no power to the blower fan for heat and staring the the electrical diagram has not helped. The E24 has relays, not sure about the E12. This is from an 84 633, not e12-based but perhaps helpful.

 

[bavarian]

Hey so what I did was I checked power at the fuse and I had no power there so I opened up the fuse box and there wasn’t even a power feed ? But some people say that this relay has melted fuse boxes, at least in e12s it has, I’ve seen people fix the wire at the glove box and be ok, I’d also check and maybe clean your fan speed switch it’s a bit of a job but mine was super gunky

 

[bavarian]

Can also bench test your heater blower to rule it out. Also check it anything happens at full speed , if it comes on it’s the transistor

 

[Ohmess]

If I am following this thread correctly, you don't have power at the fuse to the heater blower motor. Upstream from there would be the unloader relay. The unloader relay shuts down heater (and a/c) fan when you go to start the car. It is located under the dash on the inside of the left front fender.

 

[Beaudave]

Hi guys,
I'm carefully reading this thread because my blower also doesn't get power. I tested the fan directly from the battery, and worked perfectly. It seems that me too, the wires coming from the fuses have no voltage. So I was wonderning where to check next. So I will look at the fuses, and then the unloader relay.
Did any one had this unloader relay issue fixed? If so, what should be done? Regards.

 

[Ohmess]

What year is your car? Electrical differs from the early cars to the late cars.

If the problem is the unloader relay, you need to replace it. Assuming your fuses are ok, you should pull the relay and test it separately.

If you post the year of your car, I can provide more detail on testing.

 

[HB Chris]

In 1974 the unloader relay was removed and that feature was added to the fan switch. I would check to see if you are getting power to the fan switch itself. If the compressor turns on then you do have power as it comes from the fan switch to the temp switch and then to the pump.

 

[Beaudave]

What year is your car? Electrical differs from the early cars to the late cars.

If the problem is the unloader relay, you need to replace it. Assuming your fuses are ok, you should pull the relay and test it separately.

If you post the year of your car, I can provide more detail on testing.

Hi Chris,
I successfully got this problem fixed yesterday. It was indeed one faulty relay. I don't think it is an unloader relay, but a simple power relay. Because the headlights were still functioning okay. So I just ordered 2 models of 4 pins relay (because I noticed there are several widths of pins...), and boom! Was working again. Anyway, thanks for the advice.

 

[Beaudave]

As some others would say, I took a chance while "I was at doing it", to dismount the heating control panel, so as to clean it up. I found that there are 2 little light bulbs to illuminate the control panel. (Funny enough, I thought there was none, because no light at all when I got the car, and there is a light beam coming from the steering wheel that kind of lights up the panel, when it's really dark. I thought... that's not usual for German Engineering...) The power wire was not welded correctly, so I re-did it. Sand-papered the electric contacts, and remounted the Blaupunkt stereo... Trying to do things right. And finally, found out that all I needed to check is that G*ddamn relay!