Aaron91RS

iTrader: (2)

Not my car but got my friends 92 TBI firebird.
The fuse is good but nothing works. The a/c compressor won't kick on.
The heater motor won't come on.
So here's what I diagnosed so far.
The blower fan relay under the hood gets main power on the thick red wire, but the switches inside won't give any power to the little orange wire to trip it. I manually tripped it by connecting the orange wire to the battery.
That makes the fan come on, but I still can't adjust it's speed from the controls inside. That seems weird to me because at that point by jumping the relay I figure it runs through all those resisters that change the speed.

Next thing I did was jump the a/c compressor on the battery. It to then comes on.

Lastly I pulled the switch box from the center console just far enough to make sure everything was plugged in and at least moving. I made sure the center electrical connecter behind the switches was good.

Lastly the lower switch inside does change it from coming out the vents on the dash vs under the kick panels, but that switch is on a manual wire not electrical so that makes sense.

At this point I'm not sure what the next step is.
With EVERYTHING being dead it's almost like it's not getting power from the fuse box even with a good fuse. Is there any single power feed wire behind the inside controls for all this stuff? If so I might just run straight power to it to see if anything works then. Unless someone has some other ideas?

BigBadLou

iTrader: (3)

If the HTR A/C fuse is good, then I'd look at the connector at the back of the HVAC controls. That's the only thing that stands between the fuse and the blower motor. See in this diagram.
The ground is good if you could turn on the relay an the fan at high speed.

Hope this helps.
Lou

Aaron91RS

iTrader: (2)

OK this is the weirdest thing. If I pull the wires out from the blower motor relay under the hood, the little orange wire will ground to the little black wire. The red wire has voltage and will ground to the purple wire causing the fan to come on. For all practical purposes the relay should trip and it doesn't
For some reason even though the orange wire is getting power it's so little it can't even trip the relay. I can trip the relay just fine off the battery

So I pulled the switches inside again and jumped 12'volts from the big rectangular plug brown wire to the orange wire on the other square plug and the blower fan came on.
So somewhere in there I guess it's someone losing to much voltage.

I thinking that circular plastic piece held in by two screws right behind the switch panel that changes connections as you move the top switch across.
http://www.autozone.com/selectedZip,.../selectZip.htm