I have a 2002 S-10 Blazer my problem is when the heat or a/c is turned off I still get heat blowing thru the defrost vent and also down by my feet. This would not be a problem but I live in Fla, and its hot. If I turn on the a/c the problem goes away. I don't hear any vacum leak. I'm not sure what to check next. Any help?

 

Welcome.

Read the owners manual and make sure you don't have the vent controls set to fresh air. At least one of the settings is to draw in outside air, even if the fan is off. The engine compartment heat and air movement can make it feel like the heater is still on.

 

I have the fan turned all the way left (low) along with the vacum control switch set to off (turned all the way left). I still get heat blowing through the faster I drive the harder it blows. Is it possibly the heater control valve or something called the blend door?