Interior Fan

[Gus 5]

my fan only works on full.....any ideas as to how to fix this? beginning to irritate me

[bimmer boy 21]

me too

and wen it is on full its barely putting out any air like as if it was on 1

[Grant 4]

Gus/ Ryan

It is a common problem, I can't recall the fix for this, but I'll try and find it.

Cheers

[bimmer boy 21]

just copeid and pasted this from a site , it might help

E30 Blower problems.

The fan in my '90 325iC stopped operating in the 1,2 and 3 position but will operate in the 4 (highest) setting. I think I once read something about replacing a "fan control module" or something similar in name. If anyone has information or a previous post which describes how to diagnose and resolve this problem I would greatly appreciate it if you would e-mail it to me at tbigham@lehman.com or post it publicly. As my Bently has been ordered, I intend to DIY this repair.

Thanks in advance,

Tim

Tim,

This sounds like something wrong with the Blower resistors or safety switch. When the control is in pos 1-3, current goes through 1-3 resistors and a overheat safety switch before going to the blower. In pos. 4 current goes directly to the blower. Since it doesn't work in pos. 1-3 I would suspect the safety switch or the resistors. On the '88 the safety switch is inside the blower housing accessible from the engine compartment, behind the cowl cover. The resistor is the most common failure, however.

> ...I found out

> that neither the fan or the AC work at settings 1 to 3, but do work at

> setting 4 (max fan speed). Nothing at all happens at 1 to 3.

Common problem. BMW uses series resistors to reduce voltage to the fan and produce the slower speeds. You just lost the resistor board. The AC doesn't work because it senses the airflow before it turns on.

The resistors are easy to fix, but somewhat hard to get to. Look on the top of the firewall from the engine compartement. There is a section about 18" long by 6" high right at the top which is removable with a couple of screws. You will probably have to take off a few wires and tubes from the firewall as well. After you remove that section you will see the top of the HVAC unit sticking out of the passenger compartement. Remove the plastic cover (held on by a couple of straps if I remember right) to see the fan. The fan motor is a horizontal cylinder with a squirl (sp?) cage fan at either end. The resistor board is slid into the HVAC case below the fan. It is a small board, about 1-2" square, with 3 bare wire resistors on it. You pull it out toward you, nothing to detach first, it has plugs on the far side. Either you lost one of the resistors, or the contacts are dirty. Check it with an ohm meter. Installation is the reverse of removal ;-)

good luck,

[E30-323ti 66]

I had the same problem.

Was mentally preparing to replace the resistors etc...

But then, fanged out of the Mobil near the Napier turn-off, rather sideways, and wal-lah, fixed!!

Works on all 4 settings now!!

FYI, it was the south exit and I was heading north if you wanted to give it a go.

[Gus 5]

glenn, ive heard bout that fix. done my fair share of fanging. still doesnt work. must need to fang some more.

[gmccormack 0]

The resistors are fitted directly to the fan motor, have a look at the one I have out of a prefaclift car when you pick up the other parts you want Gus.

[bimmer boy 21]

heres a better set of instructions on how to fix the problem and has pictures to help

might try this after school tommorow

Ventilation only works in high (4) position ........ How to solve it

[Bids 0]

It appears that I have a similar problem but in a E39 528 with Automatic Air Con. Intermittantly the fan speed ramps to full. Usaully this is for brief 1-2 sec bursts. But recently started to remain in highspeed. The fan speed on the display remains where it was set. Now the fan remains running even when car turned off and key removed. Pulling fuse is the only way to stop it. However in a strange twist sometimes the fan remains controllable but runs very slow even on max speed. Sound very similar doesn't it. Dont know much more at this stage but are hopeing to get hold of electrical diagrams so I can trace properly. Electronic Tech by trade you see

[2002 1]

I had a similar problem on my E36 with climate control. Instead of a resistor pack

there is a module (basically a very large transistor) which controls the fan by pulse width modulation. On the E36 this module is above the transmission tunnel, against the firewall. It has large heatsinks on it, and is inserted in to the air stream from the fan.

If you've got a 'scope you can check the input and output wave forms. A multimeter will

measure the RMS voltage so you can get an idea of what's going on if you don't have access to a scope.

I've got the wiring diagrams for the E36, which I could pdf and email if you like

[Carl 3]

I had that same problem, fan only worked in position 4, got an auto electrician to fix it under the car warranty so was for free. My understanding was he just replaced the rheostat switch but he may have replaced the resistors aswell.

Kinda on topic but does anyone else get the feeling the fan is on when travelling at speed, ie, when doing 100kph with the fan turned off it still feels as though the fan is on setting 2 by the amount of air still flowing through it...

[petone 0]

yep, so i normally don't bother with the fan.