1999 Chevy Venture Heater Control: The air circulation control doesn't seem to be working. when I switch it to outside air the yellow light comes on but it stays on but dim on the inside recirculation switch. I went in where the inside air filters are and the flapper is not opening or closing no matter what switch I push and it open about 1 inch. What if any is the common problem here, the switch or the the flap activator (electric or vaccum) and how hard is it remedy the problem!
By far the most common problem is a vacuum line leaking causing this problem. Check around in the engine compartment for any small hoses that may have come disconnected or cracked and leaking. The hose picks up it's vacuum from the engine, and sends it through the firewall via a small vacuum hose, to the heater control unit.....check real close ,,,and id there is no leak, the control switch will have to come out and be inspected/replaced.
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Thanks for asking!
35 years Master Mechanic
Reply to Virtual Wrench's Post: You stated the control switch may need checked, is this the one on the dash or the actuator on the air filter box
Check to see if there is vacuum to the actuator first, then pull the control unit on the dash and check for vacuum there, let me know if you need more help...