Blower motor runs slow. Topic is solved

edaho · Post by **edaho** » 07 Aug 2016, 11:06

Hi All,

I've read most of the posts on blower motor and resistor problems but my problem seems somewhat different from those described here. My blower motor only runs at about half speed at the highest setting, and barely runs at all on the lower settings.

What I've done is this.

(1) I removed the blower motor and connected it directly to the car battery. It runs, but not as fast as iI think it should. There was some smoke residue on the motor next to the blower vanes, which makes me suspect that some of the windings on the armature might have burnt out.

(2) I pulled the resistor. It is the one with the aluminum fins, not the ceramic one. It looked fine so I put it back in.

(3) I reinstalled the motor and it runs at about half speed from what it used to.

The speed selector slide on the dash has an Auto setting all the way to the left. The motor used to run very fast in this position. Now it does not work there at all. At the far right position, where it should run fast it only seems to run at half speed. The slide switch reduces the speed as I slide it to the left and stops at the Off position.

My questions are...
Is the motor itself bad?
Is the resistor bad?
Is the switch bad?
Or is it a combination of two or more of these things?

My suspicions are that the motor has dual windings and that the high side has burnt out.
Has anyone experienced a similar problem?

I'll appreciate any information or opinions before I have to start buying expensive parts indiscriminately.
Thanks for your time and effort.

Ed

Post by **BEJinFbk** » 07 Aug 2016, 11:34

Motor has a single winding. Is it the original?
It may well be in need of replacement.

lcc014 · Post by **lcc014** » 07 Aug 2016, 13:40

My fan motor (even new) has similar issue excepted that it only happens in hot days. Winter days are fine. Could it be the resistor which reduces current output in hot days ? Because of this "feature", I need to run AC with Full motor speed '4". BTW, my climate control is manual, not ECC.

Thanks.

Post by **Ozark Lee** » 07 Aug 2016, 15:41

About all you can do with the motor, short of replacing it, is to lubricate the bearings on both the front and the rear. Getting to the front bearing is a challenge due to the squirrel cage but an oiler with an extension tube will let you place the oil in the right place. I run the motor both forward and backwards off of the battery after lubing it to work the oil in.

The power stage tends to be fairly binary, it either works or it doesn't in most cases.

...Lee

Post by **sleddriver** » 08 Aug 2016, 18:29

If it's original, it might be time to retire it. Just went through this on the sled. Found a very reasonably priced replacement + lifetime warranty on 1A autos site. At least one side uses bearings instead of bushings. Can't see the other.

Post by **abscate** » 09 Aug 2016, 04:52

I spent about three hours cleaning and lubing my 99 and got 6 more months out of it. I decided upstate NY winter sans heat was character building for about one day, then it just sucked. I bought a new one from FCP

edaho · Post by **edaho** » 11 Aug 2016, 16:15

Now the motor will not run at all at any selected speed. I guess I'll have to remove it and jumper it again. The motor spins freely enough by hand, so it's not a dry bushing.

Is there any way to test the resistor? From what I've read, this type of resistor with the aluminum vanes seldom fails.

Has anyone had any problems with the slide type speed selector?

Post by **Ozark Lee** » 11 Aug 2016, 17:17

The aluminum fin type is not really a resistor at all, it is a MOSFET transistor. They have two failure modes, one where it does absolutely nothing and the other where the blower never turns off, even with the key out. They can and do fail fairly often but usually after the fan itself drags or locks up and it draws excessive current.

The only real test is replace with known good unless you want to pull it apart. The actual MOSFET transistor is no longer available but there are some folks that have tried to substitute a different MOSFET that is in current (as of 10 years ago anyway) production. I think there is a thread on Brickboard that specifies some components and a procedure.

https://www.brickboard.com/AWD/index.htm?id=1202115

...Lee

Post by **abscate** » 12 Aug 2016, 04:38

The slide selector on a 2000 isn't carrying the blower current, it's signalling the control unit ( sometimes mistakenly called ECC here). You sound you have a classic case if motor failure in the brushes and it needs replacement.

Junkyard or new depending on your risk tolerance

edaho · Post by **edaho** » 12 Aug 2016, 11:18

Thanks everyone. I'm sure glad I found this forum. Your answers have been most helpful. I no longer feel like I'm shooting in the dark.

It sounds like I need to replace both the motor and the speed control transistor. The problem began with the motor running slow, which may have ruined the speed control.

I don't want to get used parts as they might fail quickly too. I have found some good buys on eBay and Amazon for new parts.

Thanks again
Ed