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1974 Spryte Windshield Defogger Fan

N

northern lights

Member
I'm trying to understand the windshield defogger system.

The way it's set up...the fan motor mounts it so the fan is blowing forward. Is this correct?

Seems like the fan should be blowing the other way, INTO the cab, through the heater core, up through the directional vents inside the windsheilds.

I have replaced the fan motor and when I power it, it definitely blows forward.

Should I just hook it up in reverse?

Then the the fan would be pulling the air over the electric motor body into the cab.

Am I missing something here?
 
I would think it should work the same way a vehicle would, when you put it to defrost, it blows onto the windshield, and when it is on heat it blows threw the vents toward you
 
Here's some pics of the fan / motor. See the blades are blowing forward, this would be pulling air from the cab
 

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Well you have two choices. Either reverse the pos and negative wires and reverse the motor, or turn the fan around and mount it the other way out on the motor shaft. Either way will make the fan blow the correct way.

Regards, Kirk
 
In my Spryte (1967) the fan sucks air in from outside through a wire covered shroud, past the blades, over the motor, and then pushes the air through the radiator heater. From there the air goes up in to the windshield vents.

From your photo, if you did turn the motor the opposite direction it does not look like it would fit. If there is only one way to put the motor in then there is only one correct way to put the fan blades on to get the right air flow.

If your fan motor shaft has any play forward and back, leave a small gap between the blade hub and motor casing such that the blade hub can never rub the casing. If you don't do this you might get a very annoying noise ever time you turn the heater on.
 
I have the same shroud and wire cage, it's just not there for the pic. Thank you for the advice! It just seems weird that the air is pulled over the motor but I guess thats just Thiokol rocket science :shifty:


zspryte said:
In my Spryte (1967) the fan sucks air in from outside through a wire covered shroud, past the blades, over the motor, and then pushes the air through the radiator heater. From there the air goes up in to the windshield vents.

From your photo, if you did turn the motor the opposite direction it does not look like it would fit. If there is only one way to put the motor in then there is only one correct way to put the fan blades on to get the right air flow.

If your fan motor shaft has any play forward and back, leave a small gap between the blade hub and motor casing such that the blade hub can never rub the casing. If you don't do this you might get a very annoying noise ever time you turn the heater on.
Click to expand...
 
300 H and H said:
Well you have two choices. Either reverse the pos and negative wires and reverse the motor, or turn the fan around and mount it the other way out on the motor shaft. Either way will make the fan blow the correct way.

Regards, Kirk
Click to expand...

I don't think turning the fan around will change the direction of the air flow. I see that it isn't symmetrical which means that there is a 'correct' way to install it for efficiency (or noise). So if you reverse the motor direction you may want to flip the fan as well.

Dean
 
that might not be a factory set up.. typically you have two fans (one on the left and one on the right). the blades are on top with the motor below (motor shaft vertical...not horizontal) I will take a pic and post tommorow.

Maybe the LMC and DMC machines are different. It is possible the older thiokol spryte used the setup you have. Post some pics of the interior (of the heater vents inside the cab)

Your setup looks similar to a thiokol 601 heater.
 
My 1977 Spryte had the same single motor fan as in the picture. As I recall when I restored mine I had to get the more uncommon motor that turned the direction necessary to pull the air from outside. I think it was CCW but it was a long time ago. Wasn't hard to find at the time.
 
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