I have a 96 Blazer LS. I am not getting any heat in the vehicle when I turn on the heater. There are no signs of the heater core being bad. I checked to see if a thermostat is installed and it was. I also changed out the temp. control panel and still no results. Is there a possibility that I have a flap that directs the heat to the interior that is stuck closed? does it work by vacuum, or is it controlled electrically? how do I get to the flap if needed? thanks.

 

is the blower motor working if so you may want to try to back flush the heater core, make sure your Antifreeze to water ratio is good as well.

 

Take a look at this diagram:



Check to see if the Air Temperature Valve actuator is working. This is a motor-driven actuator. I'm not exactly sure where this is located on a '96, but unfortunately I suspect you will have to tilt the dash forward to get access. If the door is closed off to the heater core, you won't get heat.

 

first, let me thank all for your help. I pulled the heater core hoses from the water pump and intake and found the nipple on the intake plugged up. I then dug the crap out of it to unplug it and backflushed the heater core and did find a lot of black liquid inside. problem solved? Took her for a ride, heard the gurgling of the heater core filling up and still no heat?..what? As I was driving I turned switch to the a.c. mode and to my suprise...hot air. turned the ac off, left it in vent mode and cold is hot and hot is cold. Obviously something is backwards or the switch is bad. Any Ideas?

 

thanks for the diagram and your help.

 

any ideas why the cool selection temp blows hot air and the hot temp select blows cool air? bad switch? or vac lines backwards on the switch panel? just got the truck and no telling what has been done to it.

 

backflushed the core. now hot selection on the dial is cold and cold is hot? do you think the contol switch is bad or a vac line on backwards?

 

Possibly, put back to original switching see if it makes a difference, if not then the vacuums what lines are switched

 

I really think it's an electrical issue, rather than vacuum. The only way you get heat is if the temperature actuator door is directing air through the heater core, and that door is powered by an electric motor. I would focus on the connectors behind the HVAC control panel. Something is reversed back there.

 

checked the hvac panel as suggested, and sure enough the plug was flipped over. being a three prong connector with identical spacing it was possible to have it connected wrong. thanks so much for your help! have the heat!