Heater problem
1996 Pontiac Transport 6 cyl Front Wheel Drive Automatic 124274 miles

My wifes van keeps blowing HTR/AC fuses. I replace the fuse & 10 minutes of driving later...POP!!! I thought it was the relay and replaced it. It lasted a week and started blowing fuses again. I replaced the blower motor...but its still doing it. I have a Haynes manual but of course there isn't a wiring diagram for the climate system...go figure!!!
The resistor looks in good shape...is there something else using the same fuse? Maybe another component is faulty.

What size fuse is blowing? It is supposed to be a 20A according to the diagram. If it is blowing and you have or have access to a fax, I'll ship you a diagram. Normally I could attach it to this posting, but for some reason, it won't let me. Please advise, Jim.

It was a 25...but I even tried a 30amp. Still blows.
I don't have a fax machine.
Can you email it to rob_ignatov@hotmail.com ?
That would be a huge help.

Thanks

Sorry it took so long to get back to you. My computer has been down. $1500.00 later, I'm back on line. Anyway, a couple of questions. Do you have an auxiliary blower system in the rear? When the fuse is out, is anything other than the blower not working, ie cigar lighter, rear blower or aftermarket equipment? Please advise.

Nothing that I've noticed. The ABS light is always on, the rear blower works fine. I was thinking I might run a couple of wires from the rear blower plug to the front blower motor, then just use the rear controls for the front fan.
Could it be the front speed switch?

Under the dash on the duct work there should be a resistor block that controls the blower motor speeds. The inner part of this block has several resistance coils for the various speeds. If any of these coils are touching, it will cause the problem you are having. Let me know what you find.