Hi everyone, new to the forum. I have a 99 Blazer 4WD, V6 Vortec. The HVAC blower quit. Fuse good. We replaced the blower motor assembly and still nothing. I probed the connections at various settings. There is a Purple wire and Black wire as well as a brown ground. The black seems to be always hot. The purple shows no voltage at any setting. My next suspicion was the resistor, however the voltage going into the resistor is the same. One wire hot, one wire reads only millivolts.

Does anyone have a suggestion?? Does anyone have a wiring diagram. Haynes does not!

 

change the relay

 

Sounds like a plan. The haynes manual is not very much help. Where is this particular relay located?

much appreciated

 

Yeah, Haynes can be frustrating sometimes, especially when it comes to wiring. Believe me, I know, lol.

It's hard to say on the relay, because my Blazer is an older model and I have the Haynes manual that goes up to '94. It should be under the hood though, I would think.

 

Open the hood, look at the rear left side, this is the black a/c box, on it should be a silver box with a plug going to it, if so that is the relay, if you screw around and jump the red and purple wire together the blower should come on, if it does than the relay is even more likely bad, if not than check the red wire for power as well as the other two black wires, oonly one of the black wires should have power when the a/c is on the other is the ground.