Blower Motor problems

[pacojdog_kic]

I am working on a 97 gmc jimmy 4.3 vortec. I recently replaced the heater core for the second time (getting easier) and i was also going to replace the blower motor because it was not working. I tested the new motor and it still did not work. I jumped the old motor (still in the housing) to the battery and it kicked right on. So now I am trying to diagnose whats wrong. I have no power going to the plug except for high. I was thinking this was a relay im just unsure of where it is located. I found a 4 relay pack on the firewall but when i test for hot wires i touched one and the motor turned over so i steered away from that area. Any ideas or pics? Thanks

[67Truckin]

I think your on the right track although I don't know where the relay is either. Hopefully someone better informed will chime in with the answer.

[Lvtrucks2000]

Your 4 relays are for the fuel and iginition and don't rmember the other two. But you may have heater control issue. May have not connected something or when you pulle the dash apart you could have lost a ground or anything. I would say pull the bezel and then pull the controller out and see if you have power there. With all the other issues coming up I think there may be a line or two for the vaccum that me either be not connected or smashed....

[pacojdog_kic]

I plugged the heater controller back in and still only works on high. I can get power on 3 of the 4 connectors on the speed control. Panel reads a,b,c,d and b (orange) does not have power. Other 3 do. Not sure if this helps at all. MIght just order a new switch, ebay was cheap enough where trial and error is not so painful. Thanks again.

[Lvtrucks2000]

If you are getting Power TO the control unit for the heater, then I think you are on the right track getting a new controller. The oarange wire May be an output from the contoller.

[TheS10]

I had to replace a resister in my truck which was gave me the same issues. The resister knocks down the voltage to the fan giving you fan speeds below full blast. When the resister goes bad the fan will only operate at its highest setting. When the fan is on its highest setting it receives full voltage which explains why yours will only work when it is on full blast. Just my 2 cents anyway