Full Size GM Truck Heat Issue

My 2002 Suburban has had a quirk that I'd love to fix, but don't want to spend a bunch of cash on. It's got manual temp control, and once the truck is warmed up, no matter where the dial is set the air blowing is full on hot. Only exception is if it is all the way to the cold setting. This makes for a freeze or boil issue when I'm in the car for more than 20 minutes... Even with the fan set at the lowest setting, it cooks.

Anybody experienced a similar issue? It's done this since I bought it a year and a half and 20k miles ago.

I did a quick search and came up with a vent door actuator GM 52474810. See if researching that part number and the threads you find reflect your problems. Rock Auto has them starting at $35, and don't forget to look for a coupon code. Rock Auto will actually post them on here from time to time.

Thanks Ross, I did some googling but didn't come up with that. Sounds like it could be the right fix and it's cheap and easy enough I'm going to go for it.