Heat always on after heater core replaced

I just replaced the heater core on my 98 blazer. When I put the dash back in, my heat adjustment doesn't work. I hope I don't have to remove the dash again. It stays on hot all the time. A/C compressors runs, but comes out hot. Any help is appreciated.

vaccume, flat pack moter, or calble driven blend door?? my guess vaccume, and my guess, you forgot to/accidently bumped the vaccume line off of the blend door actuator

I think the blend door is electric. There are both vacuum diaphrams and electrical connectors. However, I think the blend door is electric.

You might have installed a screw in the wrong place. The bolt thats on the engine-side through the blower resistor hole must be used only on that location. If a longer bolt is used it will interfere with mode door functions.

Oh goodness, I hope it's not the wrong bolt. I would rather take a beating than to replace that thing again! Any idea how to test without removing or a better tool for removing other than an extension and universal?

extention and a swivel

Oh goodness, I hope it's not the wrong bolt. I would rather take a beating than to replace that thing again! Any idea how to test without removing or a better tool for removing other than an extension and universal?

The only option I think you have is to back out the bolt almost all the way out and then see if hot air is still coming out the vents.