Blower fan AC/Defrost

Clarkwb100

Clarkwb100

Not-quite-so-new-guy
Feb 7, 2019
20
3
Sugar Land, Texas
I swapped out the plastic blower wheel for the metal Auto Zone unit, Seemed to increase airflow but not major, maybe 10% or so. Is there another motor (Part number or what vehicle to reference, please) ?

thanks
 
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olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,519
113
Melville,Saskatchewan
If you think the G body fan is bad, my 78 Squarebody barely moved any air. I may have put one off a mid 80's truck, it was definitely bigger.
 
oldsofb

oldsofb

G-Body Guru
Dec 7, 2007
765
93
Maryland
I have my case torn apart into 6 pieces (see my build thread). I may see if I can figure out if there's any loss of pressure due to the blower case inside. There must be something that can be done. Even modern GM vehicles still use that same squirrel cage design. It has to be some kind of parasitic loss in the case and ducts design. Maybe it's as simple as sealing it up better. Who knows. It's got me curious though.

Hutch
 
airboatgreg

airboatgreg

Royal Smart Person
Oct 2, 2016
1,583
113
Going back to my earlier post some blower motors that LOOK the same have opposite rotation. You will get air flow but no where nearly as much. Just for grins, s**ts and giggles reverse polarity. As I said I had my a** handed tp me on this
 
69hurstolds

69hurstolds

Royal Smart Person
Jan 2, 2006
2,087
113
It may be a function of the blade fin angles and width. It's not a centrifugal pump per se, so a tight clearance to the casing isn't a concern nor necessary.

I got a feeling once all the holes are sealed and the trash is removed with heater/evap cores cleaned out, the air flow will be sufficient. It doesn't take much to degrade the stock fan performance. The only other way I could think of is somehow getting more power to the fan to spin it faster. There are limits to the speed however.

Squirrel cage fans don't take much to kill flow. They dead head easy but since they're not in a fluid, they don't have to worry about heatup for the most part. The funky thing with the G-bodies is that the motor gets cooled by the fan tube so even if your evap or heater core gets clogged or the foam falls out of the HVAC system and clogs up the vents, the air will still flow to the motor. So it can sit and spin all day long without burning up and you STILL won't get good flow.

It'll also be good to replace the resistors and make sure the wiring contacts are clean and tight. Old wiring and shiit takes their toll on resistance (increase) over the years which can slow down your fan motor. Your results may vary.
 
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565bbchevy

565bbchevy

Geezer
Aug 8, 2011
6,316
113
Michigan
I know when I originally just swapped my original for the 4 seasons 35334 that came with the metal cage I could feel an increase but now that I completely replaced my AC set up and sealed everything there is a significant increase when on high.
 
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Clarkwb100

Clarkwb100

Not-quite-so-new-guy
Feb 7, 2019
20
3
Sugar Land, Texas
I forgot to mention... when I replaced the plastic wheel with metal.... I looked into the housing, there was a thick, maybe 5/16", dark colored sludge on the bottom of the housing. I cleaned this out. It was moist and appeared to be decomposed organic matter (leaves?) . I ran my shop vac hose as far as possible into the air line. A little clorox spray to finish up.
Yuch!
 
oldsofb

oldsofb

G-Body Guru
Dec 7, 2007
765
93
Maryland
It may be a function of the blade fin angles and width. It's not a centrifugal pump per se, so a tight clearance to the casing isn't a concern nor necessary.
Agreed on that. I put my cleaned case together (Upper and Lower Case and inside Blower Case) to see where the cage and the inner case come together. Naturally, they don't touch, but they do come pretty close to each other. I see no improvements over the factory design that would help anything there.

It may be as stated [Cage Fin Design or air loss due to leaks]

I can't remember, did anybody note their volt reading at the blower when on high? That should be no resistors, straight batt voltage. Maybe the voltage is lower than it should be.

Hutch
 
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H

hoffa65

Greasemonkey
Mar 11, 2019
156
43
Atlanta GA
It may be a function of the blade fin angles and width. It's not a centrifugal pump per se, so a tight clearance to the casing isn't a concern nor necessary.

I got a feeling once all the holes are sealed and the trash is removed with heater/evap cores cleaned out, the air flow will be sufficient. It doesn't take much to degrade the stock fan performance. The only other way I could think of is somehow getting more power to the fan to spin it faster. There are limits to the speed however.

Squirrel cage fans don't take much to kill flow. They dead head easy but since they're not in a fluid, they don't have to worry about heatup for the most part. The funky thing with the G-bodies is that the motor gets cooled by the fan tube so even if your evap or heater core gets clogged or the foam falls out of the HVAC system and clogs up the vents, the air will still flow to the motor. So it can sit and spin all day long without burning up and you STILL won't get good flow.

It'll also be good to replace the resistors and make sure the wiring contacts are clean and tight. Old wiring and shiit takes their toll on resistance (increase) over the years which can slow down your fan motor. Your results may vary.
So your saying VB the gap between the bottom of the blower wheel and the heaterbox is not a concern?
 

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