[La.Bandit]

Does anyone know a way to run the blower motor by bypassing the a/c harness? My harness is pretty hacked up and i removed the suitcase anyway. I cant get the fan to run and i know it works.
any help would be greatly appreciated, i am trying to get this thing in for paint and this is my last issue.
thanks, rick

[Squidward]

Not sure what year/model your car is, but I'll take a stab. It depends on how redneck you want to get.

Assuming you still have the inline blower fuse attached to the alternator + terminal and you still have a blower fan relay, then you can jumper a single pole switch inside your vehicle to bypass the relay. Refer to attached pic. The alternator supply wire should be a red one that runs from the fuse to the relay connector. The blower + wire from the relay to the blower is black/orange for a 67 bird, and I can't remember what it was for 2nd gens (orange or brown?).

But keep this in mind: A blower fan can draw some current, so your switch should be rated for a good 20A or so. Just go to Home Depot and get a single pole heavy duty lighting switch for a few bucks. I think the inline fuse is either a 20 or 25A. And, you will only have hi speed fan blowing.

There are better ways to do it, but I don't know how much original stuff works and what's left of your harness.

["QUICK-SILVER"]

Cars without AC still had heater fans. SO, are any of the original fan wires still there? They usually came out through the firewall behind the engine. If any of it is left, even if you have to splice inside, mount the resistor for low speeds and the high speed blower relay for high. Then use the fan like factory.

Tell us what you're working on and what you have to work with, as far as old fan wires go, and we can figure something out for you.

[La.Bandit]

Thanks for the help guys, it's a '77 by the way, all the firewall wiring seems to be there just a mess though. There was no wire going to the alternator, maybe thats the problem? I'll check my parts car to see if there is one. What I was mainly looking for is a way to trim what is not needed on the exsisting a/c harness leaving only the fan wires.
Thanks again.

["QUICK-SILVER"]

Originally Posted by La.Bandit

Thanks for the help guys, it's a '77 by the way, all the firewall wiring seems to be there just a mess though. There was no wire going to the alternator, maybe thats the problem? I'll check my parts car to see if there is one. What I was mainly looking for is a way to trim what is not needed on the exsisting a/c harness leaving only the fan wires.
Thanks again.

The big wire from the alternator is high fan only. High fan position on the fan switch trips the high speed blower relay. All other fan speeds get power from the fuse box. A/C wires doesn't effect fan operation, so once you've sorted them out you can clean them up how ever you want to. The fan resistor should have been bolted to the A/C box. It's a flat fiber type board that had wires plugged to the top and springs/resistors on the bottom of it. You need to have it and its wiring for different low fan speeds. If you took it off with the box, bolt it back someplace safe because the springs get very hot. It will be a dead short if the springs touch metal. The high speed relay was probably bolted on the A/C box also.

[Ben M.]

Since you still didn't tell us what car you are working on (a '77 A-body is not a '77 B-body is not a '77 F-body is not a '77 H-body is also not a '77 X-body) I'm going to guess.

All of the cars had a resistor block with wires going to and from it, eventually winding up at the motor on one end and at the AC controls on the other. You need to make sure those wires are still good and consistent (no breaks in them). Once that is done, you need to ensure you have a ground to the fan motor. A-bodies had the ground on the fan itself to the chassis right there, but F-bodies were stupid and had the fan ground all the way over at the compressor. Unbolt, cut AC-harness, and throw away the compressor like every other redneck idiot from years gone by and all of the sudden the fan doesn't work because you destroyed the ground to the fan. Either need to fab one up from what remains of the AC harness or make a separate one that goes from the fan motor housing to the chassis (usually on the firewall is good enough).

In addition to providing housing for the fan resistor block, removing the AC box is going to let engine and exhaust fumes in to the cab of the car, not to mention increase the noise substantially. I would at least get an AC-delete box or an old non-cracked AC box to put back in place and ensure air gets pulled in from the cowl or wherever it was on whatever car we are working on.

[La.Bandit]

Thanks Ben
Its a '77 trans am and just like you said the redneck before me removed everything but the housing and when i got it he told me the fan was bad cause it wasnt working. I did replace it with a delete panel for a cleaner look. Do you know of anyone who has a diagram of the harness? The repair manuals dont have good ones, also do you know of any companies making replacement (modern) a/c systems for the F bodies? They all seen to be for camaros or 1st. gen firebirds only. Heck I'd even settle for a diagram to make my own 3 speed relay and get rid of all that a/c stuff.
Thanks again

[Squidward]

Here's one from 78, little bit of an eye chart, but it should work. 77 should be the same. PM me with email if you want me to send you the jpeg.

-Sean