I'm looking at buying a 99 Blazer. My question is, can I drop a climate control in instead of the standard HvAC controls or is there a ton of mods that need to be made to make this work?

I'm just merely curious

 

as far as i know, you can't just swap the two systems. i have a '98 Blazer LT with the Auto Climate system-and i hate it! the damn thing never turns off the heat completely (a bitch in the summer). a common problem from day one (a friend @ GM told me, he used to get 2 or 3 of these a week for this issue, when they first came out). plus, the if the fan is on the "Auto" setting, it'll just fire the fan up to high to get the temp settled again (kind of anoying if the vents are turned towards your face). the only "good" thing i can say about it is, that during the winter, if it's turned right up (past the numerical setting) to the red "dot", it'll clear a frosty windshield pretty darn fast-regardless of how much the truck has warmed up.