96 Grand Voyager A/C question

This, unfortunately, isn't all that uncommon. Many of the damper actuators are vacuum powered. At full throttle, the amount of intake vacuum drops dramatically allowing the spring loaded dampers to overpower the vacuum actuators.

My Jeep Comanche had this problem in spades, partly because I had to run the 2.5L engine nearly wide open much of the time. It had a vacuum storage tank on it to help mitigate this, and the dealer installed a second tank after I complained about what you mention above, but even that didn't make a lot of difference. After just a few seconds at WOT, the actuators would begin to relax.

I haven't noticed this with my 96 and 03 vans, but then I don't often run them at WOT for any length of time.

Matt

Thanks.

Larry it does appear that the air switches to the defroster vents as the noise goes(comes from ) there and that's not even with WOT, just acceleration to pass or make a quick move.

These vans are like many cars today. Under full throttle operation the AC automatically cuts out so that maximum power is available for acceleration. As mentioned by others, the air flow to different vent positions is controlled by electric, not vacuum motors.