This is a 2004 passenger Astro with 77,000 miles, with rear A/C in central Florida. I have owned it about 3 months.

3 weeks ago I drove through a severe rain storm with a lot of water on the roads. Later that day when I started the van, the heater/AC blower came on full speed and would not shut off, no matter where I turned the fan switch or vent-selector switch. Even turning off the ignition and removing the key did not immediately stop the blower. It stopped after several minutes.

Since then, the blower fan comes on full speed at random times, and goes back to normal anywhere from 2 minutes to 10 minutes later. At the other times, the system works normally.

Ideas?

 

Have you checked the fuses?

 

Most likely it is the resistor pack. It is on the blower housing under the hood. You have to remove the coolant overflow and washer fluid bottles to get to it. It is directly behind them. Also look at the condition of the plug on the wiring harness. I had the opposite problem as you, all speeds EXCEPT High worked. That "pin" on the harness was fried. I had to get a replacement at a salvage yard. heater resister tracking#9405 5102 0084 7003 9627 60??/