i have a 98 blazer with computer climate control. the problem im having is behind the dash, the heater is makin a god awfull sound ie: sqeeking and kind of a vibrate sound and clicking. on top of the i cant control it between hot and cold,its stuck on full heat even when the heater is off its still commin out. any ideas what this could be as i am stumped. thanks alot.

 

Either your blend door is jammed or (more likely) the blend door actuator has failed. The computer climate control system uses an electric actuator that sits on top of the heater assembly & is known to fail. There is a small plastic gear inside that breaks & that is probably the noise you are hearing. It is located on top of the heater assembly on the passenger side. Officially you are supposed to remove the instrument panel to get to it but I managed to remove mine after removing the glove compartment, although access was VERY tight & took a long time to get the screws out. I have a right hand drive UK market model, the North American models may be different. When you have taken the actuator out make sure the blend door spindle is free to move throughout its range or you will quickly ruin the new actuator.
Once you have refitted the actuator make sure you remove the RDO/Batt fuse for around 20 seconds before replacing it - this allows the actuator to reset itself.
Hope this helps.