heater blower motor blow some CFM wired backwards

[oneblueyedog]

I inspected my heater fan today on the bench, looking for a reason for its squealing before winter. I took it all apart and blew the dust out of the armature and bushings and stuff. I checked the brushes and it looked to be about 5 years left. I couldn't find any shot bearings in it and I put it all back together. I bench ran it and it ran like it always did for the last 9 years I've had the car- wimpy. So I decided to test it backwards. Negative to the brown. Just for a second-since I want to get a Grainger conversion.


It ran! It blew debris off the bench. I decided to hook it up to the bench battery to give it a good run. It blew like crazy, absolutely astoundingly 100% better.

I ran it and was mesmerized by its power. Then it sucked a t-shirt bag in the intake-and I thought that was the end. It spit some pieces out like a limb shredder before I could yank the alligator clip off.

I cleared out the housing and test ran it again. Still blew great.

I noticed the terminals got hot on on the motor. I kept them far apart so I was not shorting them out. Why would that be? It's a DC motor.

Why would the fan work better in reverse? If It blew like that in the car it would be great.

No Squeal either. Just hot blade terminals. Weird.

I really think the squirrel cage needs to turn in the opposite direction. I wonder if I have an oddball motor. It's an original AFAIK.

[fintstone]

Maybe I misunderstand. You said "backwards, negative to brown"...brown is usually negatve (ground).

[oneblueyedog]

Yep. Brown was positive. BTW i just drove it around with it wired correctly and the rattles are back in the fan. I've unplugged it.

[Gogar]

Gosh, I think Brown is Ground for a lot of us. Is the other wire black?

Check this out; on the SC diagrams it's the first set, page 2.

http://www.pelicanparts.com/911/911_Parts/911_electrical_diagrams.htm

[oneblueyedog]

Thanks for the replies

Yep. Brown rules for ground. The other wire is yellow/black like the diagrams show in the Bently manual.

I was just messing around with it since it sounds like a bunch of gerbils in a gang fight in there when I turn the heater on.

What would make it run better when I reverse polarity of the motor, that's the mystery.

[Gogar]

So you're saying the "good running way" is Brown +, Black/Yel - ??

When you do that, does it still suck-push the right way, or does is go backwards?

Heck if it still turns the right direction, leave it!

My heater blower works, but the only way I know it does is because I hear it. I think two hamsters farting into a tube would profide more CFM.

[sammyg2]

centrifugal fans and pumps will blow and pump when rotating backwards, but not as well. I suspect your fan is running at normal speed backwards but slower than normal forwards. Prolly have to do with the brushes or commutator. Take some fine emory or scotch brite and clean them, make sure your brushes aren't worn down too far, clean them and get rid of any sharp edges, that's all I can think of.

[oneblueyedog]

Gerbil farts! That's accurate.

When I wire it Brown to + it sucks better and blows harder. But the terminals get hot enough to blister flesh.

But wired correctly it's slow. I'll check the rotation and commutator and brushes again.

Since its rattling now, its coming out and I'll get a friend to get me a fan. I'm tempted to get one that runs in the opposite direction.

Thanks!

[Limalbeps]

Did you ever work this out? I have stripped this motor to get it working and it seems to me that the fan blows harder when the polarity is switched

[LeakProof]

I just keep switching the wires back and forth until it blows the most air,then put the hose back on. not really sure witch way the squirrel cage is suppose to turn?

Mike.

[3.2 CAB]

I replaced my rear blower with on from 914 that was like new, when the tree fell on it. It is pretty much a direct replacement, but... you do have to remove your squirrel from your old blower, because the 914 cages are backwards or reverse from the direction for the 911's. The big plus side to it is that you can buy a 914 blower for next to nothing as opposed to a 911 blower. I almost forgot, the wire harness plug on the 914 motor is different, so you have to use the plug off of your old 911 blower motor along with the squirrel cage. I did this mod about 4 yrs ago, and it actually seems to be moving a LOT more air than the stock motor. Tony.

[oneblueyedog]

Beneficial resurrection. I will have my eyes peeled now. Thanks for the tip!