Automatic A/C would stop blowing cold air and start blowing hot air, as if it was switched into heat mode, while outside temps were in the 90's. One way to correct it was to shut the vehicle down and restart. I could also hear a frequent whining from under the dash (pew pew pew) as if a little motor was spinning. The heat was so hot I could not stay in the cab and had to pull over each time and restart the truck. It was not an A/C freon or compressor issue.

Took it in and one GM shop wanted $1800 to remove the dash and replace the diverter motor, another wanted $1600.

Took it to an old friend who has a auto shop and he priced it at 350 nut only had to remove the cabin cover, not the dash, so he dropped the price. Replace the diverter motor and it again works great. Now, if I could just get the automatic A/C temp adjuster knobs to perform as intended instead of jumping 5 and 10 degree increments or not moving at all when the knobs are turned.