Need help with blower motor
 

1998 Blazer 4x4 with ACC (Automatic Climate Control)

My blower motor wont start up at any speed I set it at. I replaced the blower motor, the resistor, and the control unit in the dash. Nothing. I did some searching on here and found a few posts talking about a couple sensors that the ACC uses (cabin temp sensor in headliner and air temp sensor behind grille). Could one of these be the problem? I would assume that they would only come into play when the temp and blower speed are set to AUTO, but I have no blower even at the manual settings. Also, the temp on my overhead console always reads OC. I found on here that it means open circuit, and usually means the air temp sensor behind the grille is bad but would this cause the blower not to work? Can anybody point me in a direction to look next? Any help is greatly appreciatted!!

Have you checked the HVAC fuse in the underhood fuse box?

Yes. All fuses are good. I'm stumped!

Could it be the blower motor relay? If so, where is that located?

The blower motor relay should be located on the firewall near the distributor.

I still dont see a relay. Also, my resistor looks alot different than everyone elses. Im assuming its because I have ACC? Anyways, I have 3 wires going to my resistor, orange, black, and purlpe with white stripe. I have no power to the orange, no ground on the black, but I am getting signal from the in cab fan speed control at the purple. Is the orange a switched power? Could I run a relay to get hot to it when the ignition is on? Would that work if I also grounded the black?

The orange wire should be +12V constant. This is powered by the HVAC fuse in the underhood fuse block.

FIXED IT
I wasnt getting +12V at the orange so I ran a fused link to the underhood electrical box and ran a good ground for the black. Works perfect. Thanks to all who gave their input!!!