Heater blower fan motor.

[Slackey]

I looked pretty far through the archives and couldn't seem to find too much.

My blower motor is cooked and i need a new one. Although the $180-$240 i have been quoted seems crazy for such a small and simple part. I believe i read on somebody's post that you could buy a motor on its own without the fan for just $80. If that is true, where do i find it?

Also, has anyone successfully found an alternative. I have found endless amounts of electric motors that will do the job, but would require some modification of the heater box in order to fit, for $20-$50.

Thank you for your help.

[InkaSteve]

Is it actually "cooked" , or just frozen up. If just frozen....they can sometimes be unfrozen (thawed out??).

[JerryC]

Depending on how handy you are, you can rebuild the motor yourself. I've done it on two different motors. On one other motor, the plastic brush guide had melted and the brush was stuck. Freeing the brush got it working again.

The basic steps are:

1. Disassemble - note + and - terminals. I don't recall the exact construction, but remove the brushes first, then the assembly that the brush guides are attached to. This requires some bending of tabs and drilling or grinding of swaged material. Wish I could remember how to remove the armature, but I know it can be done. Clean out the bearings as completely as you can.

2. If you have access to a lathe or a friend with one, turn down the commutatar so it is straight again. Clean out the copper that has rolled over into the commutator grooves with a sharp knife. If there's no lathe, do the best you can with a drill and a sharp, flat, wide file, steadying the free shaft end in a wooden "V" clamped in a vice. This is just a fan motor and "home turning" will do the job. You want to get down to fresh copper to minimize resistance between the commutator and the brushes. The rebuild will last much longer if you start with a straight commutator.

3. Reassemble. The secret to successful reassembly is JB Weld and your home oven. Epoxy the brush guide assembly back onto the motor frame. You can greatly accelerate the epoxy cure by baking for one hour in your home oven set to its lowest possible temperature. Add some thin oil to the bearings, no grease or you'll have a gummy motor in a short time. Don't get any oil on the commutator or the brushes.

4. Install new brushes. Now, I'm sure you can't get new ones from Bosch or BMW, so go to your nearest automotive electric shop with your old brushes. Get carbon brushes that are the closest match for wire and thickness, but too wide. They'll cost you maybe $5. You can thin down the new brushes by rubbing on a piece of fine sandpaper backed up by a smooth hard surface (a piece of window glass works very well for a smooth hard surface). Take your time, check progress frequently, and stop just when the brushes slip freely into the guides. Load the brushes and the springs into the guides and bend the tabs over to hold the brushes in the guides.

5. Apply power, it should run like new. Be very careful if you run the fan while holding the motor in your hand. Those metal blades can slice your fingers nicely.

6. When you reinstall the fan blades, spin it gently while looking for bent blades. Straighten as required.

You will be amazed at how much air this fan can move.

[Slackey]

Sounds good. My brush guides are totally melted but i think i may have found a good donor motor. Thanks.

[Harv]

I have been working on using a large computer cooling fan in my heater box. It has required a few permanent mods but I think it is going to work fine.

John

[Mjimport]

I just got the Bosch motor to rebuild my fan but of course it spins the wrong way.

 

can I simply rebuild the new motor - invert the brushes and then swap the wires?  Photo attached of the two guides held in place with a small spring, looks easy enough to swap around.

Edited March 30, 2021 by Mjimport

[DanVT]

Mjimport,

See my fan post that I just updated. In short, flip the brushes so they drag on the rotor, then flip the wire connections.

Dan

[Mjimport]

4 minutes ago, DanVT said:

Mjimport,

See my fan post that I just updated. In short, flip the brushes so they drag on the rotor, then flip the wire connections.

Dan

 

Awesome!  That’s exactly what I was thinking would work.

thanks !

[Mjimport]

Ok I successfully switched the brushes and installed the old fan blade.  It’s pretty powerful for its size!

 

next issue: how does the motor attach to the housing?

I reinstalled the 4 metal spring clips but it doesn’t really “lock in” and wants to slide out.

photo 1:

Are the clips supposed to “grab” the plastic edge of the fan motor plastic surround?  if so, the clips are extremely tough to stretch that far and I’m afraid I’ll break a few things in the process.
 

Photo 2:

Or do they just press against the side of the motor to act as a spring to keep it centered in the box shroud ?

 

edit: or am I missing something else altogether... I try to take photos of everything before deconstruction but alas I failed to take one that shows precisely how this goes together.

Edited April 1, 2021 by Mjimport

[7502]

Can you squeeze the surround together to close the gap? Looks like it might be designed to compress a bit.

[Mjimport]

40 minutes ago, 7502 said:

Can you squeeze the surround together to close the gap? Looks like it might be designed to compress a bit.

Ahh, you mean the diagonal “legs” in the molded plastic motor surround?  I didn’t think of that but it would certainly allow for the 2mm of assist to get the clips over the edge.  I’ll check that out.

thanks!

[7502]

6 minutes ago, Mjimport said:

Ahh, you mean the diagonal “legs” in the molded plastic motor surround?

Yeah, maybe that might work in your favor.

[Mjimport]

Ok, the plastic motor surround does not flex.  It is mated to the metal internals at both ends so no substantial compression is achieved.

 

any other thoughts?  Can someone confirm that the motor assembly is only held by the 4 metal clips?  Other piece I am missing?  
 

I want to be certain before applying Hulk-like force to get the clips engaged further.

 

 

[DanVT]

The four clips hold the motor assembly, nothing else. The lower part of the clip hooks under the lower black plastic surround. Try holding the top part of the clip away from its seating position so you can get the bottom hook up under the plastic surround. Firm thumb pressure should be enough to snap the top hook into place.

Dan

[Mjimport]

6 minutes ago, DanVT said:

The four clips hold the motor assembly, nothing else. The lower part of the clip hooks under the lower black plastic surround. Try holding the top part of the clip away from its seating position so you can get the bottom hook up under the plastic surround. Firm thumb pressure should be enough to snap the top hook into place.

Dan

thank you, again!