Astro heater blower not working.

Hi All,

I was working on a 91 Astro for my brother, that has a blower that does not come on. Heres what I have done so far.

1. Checked the fuses and all are ok.
2. Removed wires from the blower motor and applied 12 vdc directly and the blower motor runs fine.
3. With engine running and heater on high in the defrost mode, (blower not running) checked the power at the connectors at the blower motor and got 0 vdc.
4. Removed panel where switch is located in the dash and verified the switch continuity in the high, med and open in off modes.
5. Checked power at the connection in the switch harness. and have measured 12 vdc on pin 2 or second from the left when looking down from on top of the switch as it is mounted.
6. Because Pin 2 and 4 of the switch are a short when the switch is on high, I shorted pins 2 and 4 of the harness, still no blower running.

I have seen many posts of faulty ignition switches. Could this be it, or better yet is there a way to insure it is the problem?

So is there someplace on the web where I can view wiring diagrams?

Are there any relays that I should know about to check?

Any other tips are appreciated.

Thanks

Steve

Check the blower motor relay that is mounted under the hood on the passenger side. There are two relays there, the larger one is for the blower motor. The relay may be worn out or the connectors dirty. I had one go bad on my '92, and it did the same thing. ~$25 for a new one if that's the problem.