No power to blower - help!

[xer0trigger]

Ok, so my blower motor the last several weeks has been pretty flaky. Sometimes it works, sometimes it doesn't (all speeds). For the last several days it's been completely dead, so I decided to have a look at the various components.

First I checked the fan speed switch (in the cabin). It's getting power and sending it fine.

Then I pulled the access plate off the firewall and checked for power at the connectors to the blower motor with the fan speed set to HIGH. Nothing.

I then pulled the blower motor out and connected it directly to the positive battery terminal and chassis ground and verfied that the blower is indeed functioning fine. I also verified that the ground was good on the blower motor harness.

So what could it be? I was under the impression from the wiring schematics that the resistor plate only came into effect on the 1-3 fan speeds and not on 4 (HIGH). Yet I'm getting no power at all on the positive lead to the blower motor on any fan setting.

Any help at all would be greatly appreciated!

[lordofthewaters]

Can't help, except to say that there is a resistor for the 4 setting blower.

[emi325i]

the resistor pack.. it's under the blower. cheap to replace, or spray wd40 on it.. that usually gets it going again

[emi325i]

of course, i didn't read the whole post.

[allwheeldrive]

I had an intermittent problem with my blower also. And when it was happening, none of the speeds worked. Turns out that it was the 30a fuse was not making good contact in the fuse block. All i did was tweak the blades of the fuse in order to provide a better connection and fit in the fuse block, and its worked fine ever since. (3+ months)

If this is the case with yours, the fuse will feel loose. Did with mine. Hope this helps.

[emi325i]

that 30A fuse is dangerous.. it can't take 29A.. it will melt (I just know). If you have the blower out, blow the carbon dust out of it with some compressed air. it conducts electricity and causes an increased current draw.

[HST]

Could be your actual switch in your dash.

[hoveringuy]

My blower is starting to act up, too.

Occasionally it won't come on at any setting until I've driven for a few miles, then it will come on. It doesn't seem to have anything to do with hitting a bump, either. I'm thinking that the whatever isn't making a good connection finally heats up enough to make the connection.

I'll wait until it completely fails because it should be easier to diagnose at that point.

[hoveringuy]

Ok, it's completely failed now.

When I pull fuse #20 in and out with the key and blower on I hear a "thunk, thunk" coming from behind the blower access panel. I don't think there's a relay in there.

What's going "thunk, thunk"??

Hoveringuy

[allwheeldrive]

Blower motor seized up? Unable to spin? My original motor was like that.. Worn out and the bearings were starting to seize.

[T.Dot_E30]

check all fuses, there is more than one controling the blower motor.

I remember checking one fuse thinking everything was fine, pulled apart a few things and nothing seemed right.

Turns out there are like 3 fuses linked to the blower motor and one was blown.

[hoveringuy]

I've got the car on a truck for my move out West now (Seattle), but the blower is not seized. Lately, the blower has worked fine first thing in the morning. In the Afternoon it doesn't come on at any speed for the first 5 or 10 minutes and then it will suddenly come on and stay on.

It runs fine and doesn't make any unusual noises when it's running.

I will check ALL fuses when I reunite with the car.

Are my symptons consistent with the blower going bad?

[BimmerBob]

There are numerous parts that control the fan however there is a direct path from Fuse 20 (30A) via the Blower Switch (on HIGH) to the Blower Motor.

The Blue wire leaving the blower switch connects to Pin 4 of the Resistor Pack and to the Blower Motor.

If the Blue wire is hot leaving the Blower Switch and not when arriving at the Blower Motor then there is a break in the wire which needs to be fixed.

To determine if the wire is broken from the Resistor Pack to the Blower Motor put the Blower Switch to a Medium Position, if it works on medium and not on high the break is between the Blower Switch and the Resistor Pack. If it does not work on any speed then the break is between the Resistor Pack and the Blower Motor.

Good luck with the repair, Bob

[hoveringuy]

It went on the truck yesterday so I'm not suffering through this East Coast heat in it. I will have the opposite problem in Seattle, I'll need the blower for heat!!

In any case, with an M50 it will be more difficult for me to access the blower (anyone done this with an M50??) I'll check for power on the blue wire before I commit to pulling the blower.