A/C and Heater Blowers not working

[espoe]

i have read through the forums and found that this is probably the main blower relay located by the glove box. My Question, would this blow the 30a fuse number 16? Just checking to be sure I am going the right direction.

85 635CSI Auto, US

Thanks

[CW6er]

Are both of the blowers not operating at all, or are they only operating in high? Need more info to pin the problem down. Go to here and go through the troubleshooting in my post:
http://bigcoupe.com/phpBB2/viewtopic.php?t=14791&

Fuse 16 is for the in-dash blower control and both motors. Sounds like maybe one or both of the motors may be dragging?

[espoe]

Thanks for responding. I had looked around prior to posting and that is exactly the post I was referring to that i found. My situation is number 6. they don't come on at all and the fuse blows instantly. That's why I was assuming the relay but I didn't know if a bad relay would blow the fuse.

My other thought was the Blower speed dial but I don't know how to check that.

Should I be checking this out a certain way?

[CW6er]

My situation is number 6. they don't come on at all and the fuse blows instantly.

"Fuse blows instantly" after doing what exactly? After replacing the fuse (does it matter if the A/C button is in or out)? After turning the speed dial to "Max" blower (again, does it matter if the A/C button is in or out)? or what?

That's why I was assuming the relay but I didn't know if a bad relay would blow the fuse.

I wouldn't think so. You can pull it out to see if that stops it.

[espoe]

Good points, let me make sure the A/C button is out and the fan is off. I'll put the fuse in and start the car, turn it off and check the fuse. If still good, I'll turn on the fan switch check the fuse, then the a/c and check the fuse. See if I can isolate it. I can also switch the high beam relay over and see if the fans work.

What's the best way to get to the relay if i need to, remove the glove box?

[CW6er]

What's the best way to get to the relay if i need to, remove the glove box?

Do the other first to isolate the trouble, good plan.

To remove the blower relay; Do the 1st, 2nd, and 4th pictures. Forget about the 3rd and 5th Pictures:
http://www.malloc.nl/BMW/635CSi/page....html#refertoc

[simonkingit]

Hi, I am having a similar problem with my heater blower. My auto electrics experience is extremely limited.

I have replaced the transistor with an identical replacement in my 1982 635csi, and I have tested the 2 relays I found behind the blower control panel (Which both work). I haven't been able to test them under load, though (Don't know how).

I also replaced the heater blower fuse. But the heater still only works on high, with the dial cranked over to the max point. It doesn't work at all on the lover progressive stage.

Could there be something wrong with the dial? If so, what?

Please can you help?

[CW6er]

See your other post.

[espoe]

Just an fyi, I haven't gotten into really diagnosing it yet, hence I haven't posted in a while. Started working on maintenance parts now. Water pump, thermostat, belts, etc. Should have that finished in the next few weeks then I am going to get back on this fan issue and install a new a/c compressor.

I'll restart the post when i do. Thanks for the help I've got some good places to start

[simonkingit]

Hi all

Yes this is still a problem of mine.
I'm going to be on holiday in a weeks time, and being summer now, I really would like to get the blower working.

As I've stated before, I have replaced both the transistor for the heater blower and the one for the A/C blower, under the dash.

I've figured out that my 6er is a series behind the ones you talk about here and apparently based on the E21 model.

My temp control is a rotary dial on the left of the dash (See pic) and it works perfectly, cause when I turn it to heat (Red bit), I can feel the air get warmer. (Well that was when the blower briefly worked during winter).

The car does have A/C and that same temp dial must be turned to the right (the blue bit) to turn it on. I did test this when I first got the car and it did work, I heard the compressor kick in, but it didn't blow very hard and the bearing in the compressor are gone, so I need a new compressor, at a whopping 10 grand!!

Now, my problem is with the central control speed dial. That works both the A/C and heater blowers depending on where the temp dial is located. But they both only work on MAX. Even after replacing both those transistors.
I know I'm probably getting a short somewhere too, cause if I use the heater blower for too long, the fuse burns out and the little plastic holder melts. ( I know, not good) This is a very old car, and really has not been looked after by it's previous owners.

I have also tested the heater blower out of the car, and there's no drag in the motor, ir actually works with quite a great force. I have also tested the A/C blower when I have the dash apart when I was doing some of the under dash electrics, cleaning the carpet and installing new sound deadening, and that seems to work fine too, also only on MAX.

So, what would you say is my next step?
Is it the actual speed dial itself? (I hope not, cause I have no idea where I'm going to get another one of those, and when I had the dash apart the last time, trying to test power on the wires, I got myself all confused)

Please can you help?

Many thanks

[CW6er]

Ok, If your car is e12 based, then the Blower_Control_Repair.PDF you asked about in the PM does not apply. It is for the later e28 based cars. The concept is the same, there is a rheostat and a transistor in the blower control in the dash but the parts are different.

About melting the fuse; check and see if both of the blowers are running at the same time? Only one should run at a time and if both were running, they could be drawing too much current combined.

This would happen if the wrong relay were used (the one on the bracket at the bottom, on the back of the Heater-A/C panel). The correct relay is a 5 prong change-over relay that switches power output back and forth between pins 87 and 87a. However the Main relay used on the newer cars is also a 5 prong relay but turns the power on and off to both 87 and 87b simultaneously, which would cause both blowers to run together. Here is the correct one:

Bosch 0 332 204 401 - a 5 prong change-over relay (the output changes between pins 87 and 87a as relay operates) - in a 25x25mm metal can, usually with a purple strip across the top. (Do not confuse it with the 5 prong Main Relay with pins 87 and 87b)

[simonkingit]

Hi

Thanks Chris for the feedback.
I have looked at the relay, it is the correct one. I've also noticed that only one blower works at a time, and the fuse doesn't seem to be melting anymore. Perhaps I had the wrong fuse in it when it did melt.

I've had a look for the transistor at the control panel, and I cannot find it. None of the wires look like they've been changed or modified, so the only other thing I can think it might be is the actual dial control itself.

I'm gonna take the control unit out completely to get a better look at it.

I noticed last night that my rear windshield defrost/demister also doesn't work. I checked for power at the switch and at the window, and all is well, but still doesn't work!??

Anyway, thanks again.
Speak soon