Everytime I put a power demand on the engine my climate control system stops working. In the case of air directed through the vents the air stops blowing. I assume it stops because the damper for the climate control shuts, in effect the system is going into the 'off' mode. I suspect that there is a vacuume drop which allows the damper to close. Further more I assume there is a check value somewhere in the system to prevent reverse flow of vacuume for the heater/ac control. Anyone have an idea as to what is causing this and where it is located. Once I let off the accelerator all function returns to normal.

 

[updated:LAST EDITED ON 24-Jul-02 AT 05:16 PM (EST)]I had this problem in my 92 F-150. I finally found a bad vacuum hose. Under the hood, on the passenger side, above the blower motor, and next to the firewall is a vacuum pump. The vacuum hose that connects to that pump was shot. It looked fine on top, but the bottom was shot.

A simple way to check is to try moving the valve on the pump. It should offer resistance. Mine just flopped back and forth.

Hope this helps.