vent control not working

[mz0dw4]

I need help in diagnosing this problem. The vent control quit working. and all air from the blower is going to the floor no matter what I turn the knob to. The blower control, hot/cold control and A/C and Recirc buttons seem to work. My vehicle is a 1995 1500 Silverado 2 wheel drive. Any help is appreciated. Thanks, Bill.

[jlashbrook]

I'm not to sure on the "newer" chevy trucks, but I had the same problem on an 80's model. The problem turned out to be a vacuum line that feeds vacuum to the heater control unit. This vacuum line goes through the firewall to the heater unit. On the older models, it was a small black plastic line that went through the firewall a little left of center of truck. This vacuum line must have vacuum on it in order to supply the necessary vacuum needed to control the vent work inside the truck.

[mz0dw4]

Originally Posted by jlashbrook

I'm not to sure on the "newer" chevy trucks, but I had the same problem on an 80's model. The problem turned out to be a vacuum line that feeds vacuum to the heater control unit. This vacuum line goes through the firewall to the heater unit. On the older models, it was a small black plastic line that went through the firewall a little left of center of truck. This vacuum line must have vacuum on it in order to supply the necessary vacuum needed to control the vent work inside the truck.

Thanks, but on the newer trucks, I don't see any vacuum lines coming from the vent control module. Maybe there are vacuum lines going to other places but there are none going to the actual module where I control the vents.

[99ssconv]

check the mechanical linkage just above the gas pedal to see if it has fallen apart, if not mode actuator or control head issues.

[Bagalac]

i have the exact same problem and have replaced my controller 3 times.. they just keep going bad.. but for the record there is no linkage or vacuum controlled devices in these newer HVAC systems its all electronic...