96 pickup knocking noise from heater box. pull heat a/c fuse it stops. reconect fuse and disconect the blower it's still there. relay ? can't feel anything from what i find behind the glove box. it sounds like a rod knocking.

 

It may be a problem with your relay, or even with your heat/AC. I'm not sure how to help you fix that problem but I'd recommend taking it to an automotive repair shop near you.

 

Mode door actuator issue.

Play with the controls to find which actuator/door is making the noise.

"Probably" an ink pen or some such thing dropped down the defroster ductwork and stuck in the door. Otherwise, a stripped gear in one of the actuators.

Allan

 

i didn't know it's a electric servo i thought it was vacume. i guess i will rip a part the dash.