Blower Motor Notes

Jan 2024  R. Kwas [Comments added]

122s and 1800s shared similar two speed Blower Motors for moving Heater and Defrost air by way of a Plastic Radial Impeller.  These were simple open frame, 2 speed, DC Motor constructions with bushing motors, supplied by Electrolux, and possibly others.  The Motor is mounted on an Endplate which was in-turn secured into the Airbox from the engine compartment side.  Bushings on these Motors do get dry, loosing their lube after time, leading to noisy and/or sluggish operation, especially when cold (which is the time when good Motor function would be nice to have!), so removal of the Motor Assembly from the Airbox, and lubing the Bushings every half-century is good practice.  

Notice:  The reader will take note of multiple occurrence of words like gently and careful here...this is not by accident!

Wiring of the Blower Motor
Pressing Impeller from Motorshaft
Repair Solution Options

-----------------

Early Blower Motors had a cute little salad bowl cover...

 

...but most of them just look like this, with the wiring visible and cooled in the breeze: 

 

Removing the Motor assembly from the Airbox in the engine compartment is a simple matter of first removing color coded power connections, then six securing screws, and GENTLY removing the Motor Assembly from the Airbox, being certain not to break off any Impeller fins in the process!  

Once removed and in-hand, separating the mounting plate from the assembly to get access to the Bushing on the connector end is a simple matter of two hexnuts, but getting new lubrication to the Bushing on Impeller end, which is rather buried behind the typically brittle Impeller, is difficult.  Removing the Impeller without damaging it must be done especially gently and carefully.  See below!...in-fact, upon removal from Airbox, sometimes (some) fins of the impeller will already exhibit partial damage to complete absence, having been damaged when making contact with debris which got through the Cowl-vent Screen.  Use extreme care when handling the Motor assembly and its fragile Impeller! 

While the Motor Assembly is removed is a good time to also clean any debris or biomass which has found its way through the Cowlvent Screen and collected on top of the Heater Core.  A shop vac is usually adequate for this, but if debris is stubborn to remove, loosen it with a snowbrush...just be certain not to damage the Heater Core in the process.   

 

------------------------------------

Motor Draws High Current!  

Once the Motor assembly is removed from Airbox and in your hand, Motor/Impeller should be able to turn freely by hand (GENTLE ON THOSE IMPELLER FINS!), and motor current should be about 3-4A on low speed, and double that on high speed, when test-connected per the wiring diagram below.  Not being able to turn freely (possibly accompanied by being noisy when cold), is a sure sign of dry Bushings, and an urgent need for lubrication! 

A hard-to-turn Motor will also draw more current as this resistance to turning is translated into a mechanical motor load, and the motor doesn't know any difference between the load it is normally driving (Impeller moving air), or simply turning itself against a high turning resistance caused by lack of lube!  [LUBE THAT THANG!]

William Snellman material, shown with his kind permission.


That's a lot of (waaay too much!) electrical power going into that motor, even at high speed! 

My response to this video and a question on the high current being drawn by Blower Motor on

"10A running and no freewheeling when power is removed, pretty much confirm very dry and draggy bushings desperately needing lube!...EXTREMELY CAREFULLY remove the BRITTLE Impeller to get access to the Bushings and soak a light oil into them (OR don't take a chance on breaking the Impeller with removal attempts, and do the best you can with a bent snoozle attachment)...

I like, prefer, and recommend Tri-flow ([light oil] with PTFE particles) for this...use WD if you want to repeat this operation in two weeks...just sayin'. WD is mostly solvent and leaves little behind in the way of long-term lube. As a lube, WD sucks IMO!  Cheers"

Follow-up question as to if the impeller was made of nylon: 

"All I can say about the impeller is that it is (was) of some sort of molded plastic, which has long ago lost all its plasticizer, and so is brittle as untempered glass at this point (something I believe you're familiar with!).

Some guys have successfully removed the impeller from the shaft with a suitable (or modified) puller, but many attempts have also broken bits off the impeller blades...nylon does absorb moisture, but at room temps, it would take an age for any significant ingress [of moisture from being wrapped in a wet paper towel] to help with removal from shaft...and WD sucks! Cheers"

 

Bill's After Power-up test:


That looks more in line with expected current at low speed. 

----------------

An interesting screenshot from a Jason Hughes video, shown with his kind permission.  He advises (and insists!) the modifications on his car were made by an engineer Previous Owner. [...who may have had too much time on his hands, or who just had to satisfy his curiosity of seeing what was going on in that Airbox, and who had just happened to have gotten a new Craftsman Sabre Saw, for Christmas, from the wife!] 


PO "Special Engineering"...I also spy some additional, non-oe plumbing...I just wonder what else was going on under that hood?

 

------------------------------

Reference Information:

Wiring of the Blower Motor: 

The Blower Motor is a two speed type.  High speed is obtained when both 1/1 AND 1/2 Terminals of Motor are powered (the first running position of Switch), and low speed is obtained when ONLY 1/2 Term is powered. 


Cleaning reveals the Terminal markings for correct wiring.  Yellow is 1/1 term, Orange is 1/2 term, center is chassis return.  Clearly visible is also the Motor Shaft, where several drops of lube should be applied to the Bushing on connector end.

Wiring Detail:


Sequential nature of power switching is shown incorrectly on the early 1800 Wiring Diagrams, but correctly on the 122 WDs.  See also:  http://www.sw-em.com/1800_Light_Switch_Wiper_Switch_Fan_Switch_Drawing_Corrections.htm#Fan_Switch   

 

George A Minassian pictures used with his kind permission.

Pressing Impeller from Motorshaft on a press...

...ULTRA-CAREFULLY, and well supported near the shaft!!


Fixturing for Impeller removal...hopefully not destruction...!

 

Bushing frozen to Motor Shaft can be gently persuaded to release by lubing and applying modest and ever-increasing torque between the two: 


Freeing a seized Bushing from Shaft in a soft-jawed vice.

 

Disassembled Blower Motor showing the Brush-end Bushing and Oil-shield Washer.


The oe Bushing is a porous material which should be well soaked in lube so it can once again, give decades worth of service!  Simply applying oil multiple times and allowing it to soak in by capillary action is ok, but William S shows the optimum technique...:

Optimum process for reoiling porous motor bushings...place them in a container with lube oil, draw and release a vacuum in the container...the lube is drawn into the pores of the bushing recharging it and allowing it to function well for the next fifty years... 


Recharging a porous motor bushing. 

-----------------

Repair Solution Options: 

Damaged Impeller: 

If a broken Impeller is encountered during disassembly (or occurs as a result of forces on the brittle assembly), the level of damage must be considered and assessed.  A chip or two off a blade not seriously affecting the balance might be ignored, and "lived with".  More serious chips which cause an obvious imbalance might be balanced out" by "clipping away" an equal chip on the opposite side (of course this will decrease its effectiveness), but again, this could be "lived with"...

If an Impeller is damaged to the extent that it must be retired, I found a lot of possible options for 3D printing a replacement when searching "3d printing a centrifugal impeller".  This could be an interesting project I leave up to the reader, but if you undertake it, I invite your feedback!  

-----------------

Bushings/Bearings:  

A gentleman also reworking his Blower Motor found the shaft was 7mm and Bearing OD was 22mm, and reported he found that a standard roller bearing of that size "fit directly" into the motor housing.  [I have not confirmed this info!]

-----------------

Brushes:

PLACEHOLDER FOR REPLACEMENT BRUSH INFO

Size: 

Source: 

An industrious gentleman reports on , that his Blower Motor wore out its Brushes, he...

 "...went to Ace Hardware and went through their brushes for drills and saws found some "sorta close". A little sanding got them to fit and a little soldering later the fan worked again." 

I've asked his for any other details he might have recorded, but it seems like any equally industrious owner could certainly reproduce his results...!

-------------------------------

External sources are attributed and shown with thanks!  Otherwise, this article is Copyright © 2024.  Ronald Kwas.   The terms Volvo, Bosch and Electrolux.  I have no affiliation with any of these companies other than to keep their products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here.  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles, and future! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you donít, youíre just a lazy, scum sucking plagiarist, and the Boston Globe or maybe Harvard wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the unique metaphor and probably (likely) wise-a** comment. 

 

B A C K ! . . .to Tech Articles Index Page