Strange heater problem

[Russ]

My daughter took my Envoy to work today. Came home and told me that the heater blower wasn't working. (I replaced the blower module when I bought the Envoy at the beginning of Dec.) Told her it was working last time I drove it and she said it worked when she went to work but not on the way home. I went out to check and sure enough it wasn't working.

Shut the car off, turned the key to on and the blower started working. Started the car and it stopped working. Turned the key to off, then back to on and it started blowing again. Back to start and stopped again.

Went in and got my key and started the car and the blower was working. Shut off and restarted and the blower was still working.

I know the ignition switch controls quite a few things. Could it be the ignition switch?

Thanks

Russ

 

[RayVoy]

I can not tell from your profile, what Envoy model you have (auto, or manual controls), sorry, I see it in your signature. You will have a blower control module, where as the manual HVAC trucks will have a blower resistor assembly (I used speed control module when I wrote the fix)

When you changed the speed control module, did you use one that plugged into the wiring harness, or did you get the newer one that required splicing the wires?

Either way, it looks to me like a loose/poor connection at the speed control module.

Turn it on and move the wires at the module, it should start/stop as you pull/move the wires.

If it is the newer one with splices, you have a loose splice; if the older style, with a connector, you need to change the connector for a new/tight connector.

Just a note (now that I know you have the auto system) the heat generated from a poor connection in the connector has been known to destroy the motor control module transistor. If you think it is the motor control module, come back and we can help you repair the module instead of replacing it again.

 

[Russ]

Replaced the ignition switch and so far, everything is working as it should.

Russ