1999 Suburban, fan stuck on high, will not change speeds or turn off when off is selected. Rear heat and fan work fine. ANY IDEAS???

Could be a relay.

Could be either the switch or high relay. If it's running with the ignition key "off" it's the relay. If it runs with the key in the "run" position it's probably the switch.

My son just replaced the fan switch on his 98 K2500 and he got the switch at NAPA for $20. I was surprised that they had it, I figured that was a dealer only item.

The switch was bad, it had partially melted.

Thanks Jeff