Hi Everyone! I have a 1985 firebird that "had" a tpi 305, this was removed for a 350 carb. Project is nearly completed, however the A/C controls don't contrl the blower motor. Blower motor works fine when I hook up direct popwer, but the controls above the radio doesn't turn it on nore control speed. Can anyone provide wiring diagrams for the A/C contrls? Also, I wanted to know if the cpu of the car is crutial to the operation of A/C, Im trying to eliminate the cpu totally.

 

ECm has nothing to to with the blower motor.
Have you checked the fuse ?

 

There should be 3 wires that connect to the Heating harness just above the heater core those used to go to the harness that wrapped in the fender and to the Computer make sure they are connected....One is a big Red one that supplies power to your blower motor

 

OK, studying the diagram provided by deadbird *(my hero)* I can assume that the ac control head and the blower blower switch is the one unit about the radio in my firebird, three wires come frome the switch, two going to the blower resister and one going to the high speed realy. Can anyone explain where the two items are, the risistor and the highspeed relay? Is it inside the car or in the engine bay, etc. And can I assume then that the compressor is told to kick on through the blower switch? Or deadbird can you provide the wiring diagrams for the compressor? 3GTAs1TA1Z28 is mentioning something to do with the cpu and Im trying to completely eliminate the cpu. In the mean time I will do my best to follow the wires from the blower switch to find the resistor, and the highspeed relay. Atleast one of those systrems must be blown or disconnected to stop the blower from being controled.

 

The Wiring for the heating controls (Unless its digital gauges) goes straight from the heater controls right thru the Firewall then to the blower motor, relays, and ect... with that in mind there are three wires that connect to the harness that comes from the harness that is/was (which ever the case maybe) connected to the Computer.... I have attached the pictures of the 3 wires and the crappy Grey connector....(Which supplies power)

 

No hero.. believe me... lol. I might make things worse for you by the end of this

Yes.. the 'control' and 'blower' are inside the car on the "one unit" (hvac) control.

There are three wires as 3GTA stated.. the 'yellow' somehow didn't quite make it through the cleaning up of the image apparently (didn't notice myself.. oops).
The third wire is yellow (the text telling wire color is there though.

The wiring passes through the firewall behind the passenger side head along with two hard plastic vacuum lines. This is the wiring from the hvac head.

The resistor pack is on the actual blower box. Should be fairly obvious if you notice the wire colors at the plug.

I don't have my book in front of me at the moment and for the life of me, I can't remember the wiring to the ECM.... but, I sort of half-ss know it just from sorting it out before.

IIRC, the ECM is tied to the switch on the back of the compressor head or the clutch wiring. The clutch itself had a green and black wire right at it. Trace the green and it should tie to a splice. The splice should have at least one green and similar green (maybe light gn or green with a stripe). The solid green is what goes (or went in your case) to the ECM for the input signal. For what I remember, this triggered the call to run the coolant fan and upped the idle slightly if the car was sitting stopped so the comp. wouldn't drag the idle down.

Don't quote me on any of that as it's mainly from what little memory I have left. Hopefully some can confirm that right or say I'm smoking crack and way off base.
Pretty sure it's close to correct though... reassuring, huh ? lol

 

I think the yellow wire you are looking for is for the cars that only have a single relay for the Blower controls....I have re-wired this whole car with a Donor harness from a 87 GTA (With a Digital Dash) The donor harness has 2 relays 1 for Low, Med, and a little higher....Then a 2nd relay for High.....Hence the missing yellow wire the old harness that was removed had the yellow.....I was just refering to the Big red wire that gets a bad connection over time.....

 

I just have to say this is great info! You guys and this site is awesome!

OK, I havn't gone to the car yet to try and find these wires, going to do that this weekend, as for the compressor, so the only reason why the cpu was needed was to up the rpm and turn on the second fan right? As far as I can remember offhand, the blower motor had the terminals that was positive and negative to turn it on, (that's how I tested to see if it worked) and this flat harness on the side that had three or four wires, I'll get pictures over the weekend, I think I'll be able to figure it out with you guy's input. There was that one wire harness that was on the dryer, that silver canaster, I think that's what it's called. You guys know what that is? I know that the compressor stopped when that was disconnected.