I have started fixing small things on my 78 Pace Car and now I'm trying to get my A/C system working. My blower motor is not working. Where should I start checking? Are there common problems I should start checking first? Thanks in advance.

 

This should help

these is a fuse, it takes care of all but the high speed. The relay then bypasses the resistors and feeds full 12v to the fan for high.
The relay in on the firewall passenger side, little silver box. The resistors are inside the AC plenum just below the relay.
see if that helps. If you have more ????'s just ask

 

I only have one speed on my fan control. I have a new 3 speed switch to put in. Question is will this get me low, mid, hi fan speeds??? Or is there another elect. relay for the fan some where else? I've already changed the silver 5 prong relay connection on the fire wall. Still only 1 speed. It's the high speed but you could fool me. It sounds more like medium fan speed. I finaly have my A/C kicking in the low 50* area. Now I need the fan speed adjustment.

 

I have been working to get my blower fan to work for some time now. I pulled the blower fan out and tested the fan to see if it would work, and it always work when i had it out of the car. Then this week when I put it back in the car I realize that I did not have a ground. I hooked up the ground and now the fan works.


Locate the blower on the passenger side of the car under the finder.You should see a wire that plugs into the blower fan.One of the screws that bolt the fan to the fire wall should have a ground wire.
I hope that this helps.

 

I was looking at the drawing. Where is the blower resistor located at. If I'm reading it right. I have only high all the time. The low and medium goes through this resistor. Correct me if I'm wrong.

 

Its the high speed that is separte from the others and thats why this is such a common thread. Make sure of the ground and then ensure your connections and all are good and you should see a diff.

 

Thats correct.
The low speeds come thru the fuse at the top of the page, then thru the function switch( any position other than MAX) then thru the speed switch for Low, Med and Med High. The speed is controlled by which resistor in the resistor pac (located in the top of the AC box on the firewall) The Brown wire is Low, Tan for Medium and Lt Blu for Med Hi. The current then passes thru the appropriate resistor and out on the Dk Blu wire to the relay. If the relay is OFF because the speed switch is not on HIGH, then the current flows across the relay contacts to the fan. As pointed out by JT the fan needs a ground and it is frequently fornicated by Bubba. The ground wire goes from the fan motor frame over to a ground post on the firewall at the corner of the AC box where it is joined by a couple of other grounds, one of them is the engine harness ground that provides tthe ground path for the blower motor, wiper motor etc..
High Speed bypasses the resistors completely.. With the speed switch on High the orange wire from the switch gets the current and sends it to the pickup coil on the relay, turning it on. This then connects full battery voltage via the Red wire on the relay across the contacts to the Dk Blu wire to the fan and it should run full speed.
The Red wire on the relay is fed from the fuse link on the starter on late C3's. Early C3's with the Horn Relay distribution the high speed comes thru an in line fuse over on the drivers side.

 

If it's like a 1974, you're looking at the top of the evaporator box.

 

Thanks for all the help guys! The car is at the alignment shop today (just finished front end rebuild) I will try and get my A/C working tommorow. Thanks again.