924Board.org

[brian19600]

I am currently working on replacing the blower motor on my '78 w/ac. Only one place seems to have a used one. I thought about using a 7" radiator fan, since we are trying to blow air through a "radiator" (heater core).

Anyone ever try that? I'm sure the air flow would be excellent!

Has anyone modified the heater box? It seems inefficient that it can't blow directly onto the core, but has to go through a hairpin turn. I would love to remove the barrier between the blower wheel and the core, but I'm not really certain of air handling technology.
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78 924

[dubrict]

the turn might make more turbulence, but it's not less efficient. Think of it like putting an elbow on a water pipe, you won't lose any pressure.

I would say the stock unit would be better than a small radiator fan on the core because it sucks the air straight from the top and forces it down to the core.

I have a blower motor from a '77 if you need one, send me a PM
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1979 924 NA
2009 Chevy Impala
2005 Dodge Dakota

[brian19600]

Does the stock blower work fairly well? Based on what I've read so far, it doesn't seem to do much.

I also PM'd you.
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78 924

[SilverGhost]

The stock blower is barely useful. Its the weakest blower on any car I've ever owned.
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"Priscilla" 1981 924 NA RoW auto, metallic blue

[brian19600]

So other than doing the 944 heater box conversion, would a more powerful blower help?
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78 924

[brian19600]

I've been doing some experimentation. I have a mid 90's gm blower motor with a blower wheel that i placed in the heater box. Little to no output. Now the rotation (clockwise) may not be the same as the original based on the baffles I see in there. But it still should be pressurizing the box the same way.

Now I had a 4" low output computer muffin fan that I placed on top and tried. Air came out!! If it was a high output fan I would be all set.

What I believe to be the case is that a blower wheel (which is supposed to be more efficient than a fan blade) is not the proper way to move air in this particular designed box. A fan blade would work better.

thoughts?
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78 924

[924RACR]

I'm confused... what do you mean blower wheel vs. fan blade? Fan blade as in the original style, blower wheel like the squirrel-cage style?
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[brian19600]

Yes, the non a/c cars used a fan blade and the a/c equipped cars used a blower wheel.
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78 924

[ideola]

[brian19600]

Nope. At least with the '78s with a/c (M573) , they only had one fan motor w/ a blower wheel. Refer PET illustration 813-20.

There is a flap next to the battery that gets opened to suck the cold air out of the evaporator assembly and down into the heater box for distribution.

A dismal sounding setup.
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78 924

[ideola]

[brian19600]

LOL I wish it did have 2 blowers. From what I understand now, the heater motor was poor at best and then it has to suck conditioned air from 4' away.
Were they under pressure to keep development costs down?

On a different note ideola, do you still have that manual radio antenna for sale?

thanks
brian
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78 924

[924RACR]

That truly is a wierd setup. My guess is they were trying to improve on the first setup, which was lame; I think in a properly-designed airbox the squirrel cage/hamster wheel flows better, but you've hit the nail on the head and they cheaped-out and didn't include the box redesign it needed.

IIRC the later, successful implementation of the wheel used them oriented in the vertical plane, blowing downward into the box, same orientation as the fan blade style.

It's especially telling, to me, that they reverted to the fan blade in '79...

I still would love to see a revision/upgrade to this, as my '82 931 still has the crappy fan blade.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[brian19600]

Yeah I can't understand why they went with a blower wheel instead of a fan with the a/c version. By the way, this 77-78 924 setup is also on a 74-77 Dasher w/ac.

I would have thought with the German winters, the heat would be the best thing on the car. Maybe the heat output from the beetles (or even worse the vw buses) desensitized the people to what good heat is.

I just ordered a jumbo muffin-like fan I'm going to try.
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78 924

[Julian]

I used the blower fan from a 911. I had to turn the shaft down a little and shorten it a bit. I have the part number in the shop if interested. Worked fine in my 78.