i dont really know what this could be so if ya'll could help me out, that would be great.
my truck blows heat from the engine through the vents inside even though the air is completely off. it only blows when im driving, not when im at a stop or just idiling.
does anyone know what this is and how to fix it?
it would be a big help, and i would really appreciate it.
so just let me know

 

close your vents? if it is an older truck there are slides throughout the cabin to close

 

its a 96. and the vents are closed. but its blowing strong enough that you can feel it through the closed vents

 

flip it to recirculate instead of fresh air

 

i appreciate the help, but that doesnt work either.

 

Your circulation door is probably not sealing right causing outside air to be forced in. You have to take the entire dash apart to fix it

 

Have you verified that the blower is actually turning off; you can hear that it's not spinning, right? If it's one of the Chevys with the cable operated recirc doors, the cables develop all kinds of fun sticking problems and don't work properly. I don't really know anything about domestic pickup trucks, but I remember a few coworkers having a similar problem.

 

You have a Climate Control Panel (CCP) that switches the blend door, blower motor ect... to control air, heat and AC in the cab. If this is working properly, the problem is in your blend door. You can usually get access by removing the lower heat core access panel and see if the blend door linkage is off, or the spring is off or broken. Your CCP controls a motor that in turn operates the blend door.

If no mechanical fault is found at the door:

1. At the mode door actuator, check the Brown wire for 12 volts.

2. Check the Black wire for a good ground.

3. Check the White wire voltage from the control head, it should be about 1-volt in defrost, 12 volts in A/C, and 6 volts in heat mode.

4. If voltages check OK, replace the mode actuator. If not OK trace wires to control head, verify powers and grounds, replace control head.

 

I have a blazer, does the same thing when vents closed but the air in mine comes out under the floorboards, its common, i mean its a chevy, I just turn the knob all the way to the blue so cooler air comes out.