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Heater blower motor failure - have I done all that I can?


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I'm trying to get the blower motor on my '74 Tii with Behr AC to spin.  I tried to get SCR in CT to fix it, but Nate there was almost certain that it would work if it was lubricated and I don't think it is something they are keen to do.  Below are some specifics of what I have done or tried so far...

 

  • I am getting about 12v to the motor terminals 
  • this goes to close to 0 when I turn the fan switch to off 
  • likewise the voltage goes to about 0 when I have the fan switch on and turn the AC on 
  • the fan will spin (stiffly) when I move it with a screw driver
  • I sprayed Tri-Flow in the bottom bushing as best I could with a long, bent spray can nozzle extension
  • I loosened the small plastic upper bushing cover and tried to get the nozzle pointed under it and gave it a good spray, I could not totally move the cover out of the way because it is too close to the outer plastic cage

 

Before I resign myself to trying to move the AC evaporator out of the way enough to pull the heater box is there anything else I might try - hitting it with a hammer, heating it with a blowtorch, rubbing a monkey paw?  I am thinking I could drill a hole in the little plastic cover and then soak it good that way, and then using some sealant to cover it again.   But I am afraid it will be futile since I know the fan is not seized. 

 

Any advice is appreciated!

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If it is still stiff when trying to spin it, I'm guessing the Tri-Flow has not reached the bearings.  Here is a thread talking about fan lubrication,

 

https://www.bmw2002faq.com/forums/topic/244057-heater-fan-lubrication/?tab=comments#comment-1347718

 

where I posted the following photos.  That is some tiny weed-eater fuel-line between the tubes.

 

001.thumb.JPG.f5e30451856360ed8054c7363dcbd52f.JPG

 

011.thumb.JPG.b3b06c918a537f5a6c31c5b4a84844bf.JPG

 

Sometimes it helps to melt and bend the tip, to be able to shoot from a different angle.

 

001.thumb.JPG.059d6e2ffb7dc6efc915be488df7980e.JPG

 

Sorry I don't have more to add... other than keep squirting!  


Tom

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Before I got my 68 back on the road it sat for 20 years, Blower didn't work, But I didn't feel like ripping dash apart. From engine compartment I turned it with screw driver on fan blade, I then sprayed Kroil on top of shaft where bearing is and repeated a few times over the next week, Then I dripped some Marvel mystery oil on it and it works now, I try to run it even when I don't use it to keep getting oil in it, So far so good

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5 minutes ago, rcf925 said:

Before I got my 68 back on the road it sat for 20 years, Blower didn't work, But I didn't feel like ripping dash apart. From engine compartment I turned it with screw driver on fan blade, I then sprayed Kroil on top of shaft where bearing is and repeated a few times over the next week, Then I dripped some Marvel mystery oil on it and it works now, I try to run it even when I don't use it to keep getting oil in it, So far so good

+1 ... did the same on the '68 1600 I once had. Ended up rebuilding the heater box anyway. All the flap pads and cables were barely operational.

Jerry

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47 minutes ago, '76mintgrün'02 said:

If it is still stiff when trying to spin it, I'm guessing the Tri-Flow has not reached the bearings.  Here is a thread talking about fan lubrication,

 

https://www.bmw2002faq.com/forums/topic/244057-heater-fan-lubrication/?tab=comments#comment-1347718

 

where I posted the following photos.  That is some tiny weed-eater fuel-line between the tubes.

 

001.thumb.JPG.f5e30451856360ed8054c7363dcbd52f.JPG

 

011.thumb.JPG.b3b06c918a537f5a6c31c5b4a84844bf.JPG

 

Sometimes it helps to melt and bend the tip, to be able to shoot from a different angle.

 

001.thumb.JPG.059d6e2ffb7dc6efc915be488df7980e.JPG

 

Sorry I don't have more to add... other than keep squirting!  


Tom

I saw your technique earlier!  I found some 50" long nozzle straws that work well - but I haven't heated and bent them yet so I'll try it.

 

 

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49 minutes ago, rcf925 said:

Before I got my 68 back on the road it sat for 20 years, Blower didn't work, But I didn't feel like ripping dash apart. From engine compartment I turned it with screw driver on fan blade, I then sprayed Kroil on top of shaft where bearing is and repeated a few times over the next week, Then I dripped some Marvel mystery oil on it and it works now, I try to run it even when I don't use it to keep getting oil in it, So far so good

 

Just now, GDI said:

I saw your technique earlier!  I found some 50" long nozzle straws that work well - but I haven't heated and bent them yet so I'll try it.

 

 

Marvel Mystery Oli - I hadn't thought of that. If the tri flow doesn't  cut it, it will be next on my list.  Thanks

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12 minutes ago, coloincaalpine said:

I have had some luck drilling a small hole thru the plastic cage and thru the plastic bearing cap to get the nozzle to the upper bushing.Also , spraying plenty of contact spray on the armature/brushes,then, keep moving the fan with a long screw driver. Good Luck

-dq

 

I'll drill it this afternoon and give it a try.  I haven't tried electronics cleaner yet - so I'll do that as well. 

 

Many thanks  - I'll update if I have any luck.

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Coupla things:

The plastic cover that (supposedly) protects the brushes and commutator ring on the heater blower motor just snaps off--no need to drill it.

 

More importantly--the Behr A/C unit is wired so the heater blower motor won't work if the A/C switch is on.  And those Behr A/C switches do go bad.  Or someone has either replaced it with the wrong switch (from an E21 or early 5er) or wired it incorrectly.  A Behr wiring diagram should be on this web site somewhere.  Check it against yours.  

 

Some lubrication and patience with encouraging the fan to turn either with your finger or a screwdriver blade with the power on will often get one going again, but if the plastic brush holders are melted or otherwise deformed, the motor is probably toast. 

 

mike 

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My heater fan died a few months ago. Last week I pulled the heater box and took the top half of the heater box with the fan attached to a local old school alternator/starter repair shop (P&H Auto-Electric in Baltimore). They put new brushes in it, lubricated and bench tested it and they said it works great. While they had the fan out of the heater box, they spray painted the heater fan blades, all for $50.  I'll be reinstalling the heater box tomorrow. 

20201122_202454.jpg

20201122_202508.jpg

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So no pictures handy unfortunately but my blower died about 10 years ago and I didn't feel like tearing out the center console and heater box.  And since the fan cage was a bit broken and chewed up anyway. . . I got in there with some diagonal cutters and clipped off the whole fan.  I then got the biggest, baddest 5.5" computer fan I could find, slid it into place, and just ziptied it onto the hole on the heater box.  Been working great for 10 years!  I mean not as much airflow as the more powerful stock fan, but still good enough to defrost the windshield on a cold morning!  If it ever does die on me, there's a pretty good looking little Spal fan for motorcycle radiators that I think would make an even better replacement:

https://www.amazon.com/Spal-30103013-Paddle-Blade-Pusher/dp/B009OBP182

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It should spin freely, so I'd do as everyone above says, and lube it well.

 

The oil after it spins is smart- tri-flow, PBlaster, etc are good penetrating

oils, but none are particularly good lubes.  A lightweight 'motor' oil

(electric motors, not gas engines) is important to keep the thing spinning

without extra wear on the bushings and shafts.  Especially as the 

shaft may very well be a bit corroded...

Where's the good old '3 in 1' when you need it?

 

t

 

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