IT IS NOT a PITA....simple pimple....you just HAVE to be able to figger it out or we would not even be having this discussion.....

beleive me when I say....

 

The screw holes are exactly the same. Even the alignment pin holes are the same.

 

At least one person here just cut his box apart and 'glased in a section so that the C4 fan fit without a spacer. This has the added advantage of unshrouding the A/C evaporator.

 

MR Vette,

My blower motor has the hot wire that goes to the capacitor, then to the hot side of the blower. Then I have two green wires that still have the factory plug on them that go to the blower. One is a little thinner then the other but they both connect into the same plug, then they slide over the top spade on the blower. Is one of those the ground wire you speak of? I don't remember seeing any other wires coming off the blower. So if one of them IS the ground that means I have to cut the plug off of it.

Can I just add another ground wire from the block to the frame of the blower? then I could leave the factory wiring intact but have a thick ga ground going to it or would that not work.

I will be doing this tonight so thanks for the help!

 

You can ground it to anything with good ground. You can upgrade the original, or you can piggy back another ground for twice the results.

 

here are some pics of my reglass effort:
http://i73.photobucket.com/albums/i2...tteScan054.jpg
http://i73.photobucket.com/albums/i209/1974vet/VetteScan052a.jpg
will add some more . . .
http://i73.photobucket.com/albums/i2...eScan051-1.jpg
http://i73.photobucket.com/albums/i2...eScan050-1.jpg
used fiberglass cloth and epoxy resin purchased at the boat supply. cut 1.5" tabs in housing used to line up the two sections.
you can see the partially modified housing on the right and how much the exit is opened compared to the factory on the left (not counting the pine straw!
http://i73.photobucket.com/albums/i2...tteScan057.jpg

 

Nice job.

 

Yeah I am thinking about just piggy backing another ground on to the fan housing and see if the voltage picks up. Those two green wires I asked MR Vette about are the grounds, they plug into the frame on the blower and then one of them plugs into another connector with a thin black wire running out and into the harness on the top of the evap box, thats probably the wiper motor ground, the other green wire runs right into the main AC harness. I am NOT cutting into all that $hit just to change the wire. My guess is that wire drops back out of the harness and grounds at the block like Mr Vette said but still I am not hacking into my harness. My original tape is still in really good condition and I am not opening that Pandora's box. I will just run another ground to the fan and hope for the best.

S489, you did a great job on the ac/blower housing!!

 

thx, was a big improvement in moving air through the ducts; i also sealed the ductwork connections using some 3M high density foam the best i could. now i can't wait to get A/C!!!

 

OK, I just got my new blower, its a 96 Vette blower but the plug is different then the C3 clower. It has a connector with 2 spades, I am assuming one is a 12v hot and the other a ground. I will test it later but i am thinking I can run my factory 12V wire to one spade, then run a thick, direct ground to the other spade from the engine block which will ground the blower directly as opposed to grounding through the frame, I will also reinstall my original ground on the frame so everything else works. It will basically be double grounded.

I will work on this tonight.
Thanks for he help guys.

 

Be careful, that second spade may be a 12V for a higher speed. I would bench test the fan using a spare car battery.

 

that should work fine, just remember to connect the wires so that the fan blows (the first time). you could leave final crimp/solder till after test. pigtails to fit fan should be at parts stores. you might also look for some materials to fabricate the little rubber boot for cooling the fan motor while there. good luck . . .

 

OK my new blower looks exactly like the blower that someone posted a pic of on PAGE 1 of this thread. IN the pic they have it mouned on the ac box sitting on the ground and you can see the white cutting board spacer on it. Notice the top of the blower motor has a big square plug on it, mine is exactly like that.

I will bench test it for sure off of an extra battery. Maybe one spade is for the high speed and the other spade is for the other speeds. We'll see I will test it after lunch and report back. It would be cool if its a ground spade though, then I can run the ground wire right to the motor.

 

Here is another thought I had about this thing....assuming I DID wire directly from the alternator to the blower, through a 30 amp relay trigged by the original relay 12V out, how would my other fan speeds work? Since the blower only gets power from the original relay and the resistor on the evap box is what triggers the relay for the first 3 speeds, (then a seperate wire from the hi speed switch triggers the relay to power the hi speed circuit) by running new wire and an extra relay triggered by the high speed circuit, wouldn't that be bypassing the original relay's capability to turn the volts down for the other speeds meaning I would only have HI and thats it? Or am I wrong on this...

Just curious...

 

I just checked the C-4 forum. The electrical plug is hot and ground. (Purple/black) Use the original wiring and enlarge the ground wire. Use a meter to make sure both tabs are isolated from the blower. One may be internally grounded. (probably not)

 

Georgious job with the glass

 

thx agin - the best/worst part is you can't see it when it's all done!!!

 

edit

 

Read the archived post:

http://forums.corvetteforum.com/show....php?t=1476553

I installed a motor and fan for a 78 in my 73 last fall. It made a big difference and no alterations, ie spacer, was needed.

Roger

Posted:
Just did this for my 1973.
Used a PM105 motor from AutoZone - it is for a 1978 Corvette. I had to make a difference vent tube since this motor had a small hole for the vent tube to fit into. Went to the junkyard and got two and cut to fit.
Install a wheel for the 78 Corvette also. It came from Advance Auto P/N 35603. The wheel is metal and about a 1/8" too narrow, but it fit and moves much more air. I am checking with ZIP Product for a plastic wheel. They were out of stock last weekend.

With this combination installed I can feel air in my face while driving with the controls in the A/C- normal position. It is not enough to blow my hair, but much better than before. Before I had to hold my hand no further than 6" from the center ducts.

Also made certain the contacts were clean and the high speed relay was working.

Using this combination the wheel speed increased from 2920 rpm to 3358 rpm with just the battery voltage applied - the units were tested on the work bench not in the car. When installed the new unit ran at 2631 rpm with battery voltage of 12.1. With the car running and an alternator output of 14 amps the motor turned at 3318 rpm with the controls in the normal A/C position and 3691 rpm in the vent position.

Further testing will be done as time permits and I get the A/C cooling properly.

Roger

 

If you had a vent tube for a 78 Corvette would this work?