Chevrolet Repair: blower speeds, chevy express, conversion van

Question
I have a 1997 chevy express conversion van that I'm having heater blower speed problem. The blower will run on high for about 30 seconds then shut off, but I can put the dial on one of the lower speeds and they blow just fine. I wait about five minutes and put the dial back to high and it will run for about 30 seconds again then shut off. I had this problem about a year ago and took it to a dealership , they said they replaced a diode or something. It has been fine till now. I was wondering if its something I can repair or a board I may have to replace ? Thank you.

Answer
depends on what needs replaced, the older cars had a diode type dealy bob, like my techincal jargon?? anyhow, it might be easy to fix but you might run into wires and al that. so.. hmmm..unless i look at it i cant be of much help. call the dealership and ask what they replaced. then go from there. sorry i can be of more help.