2015 windsport 34f, on long hill climbs my a/c changes from vent to defrost.comes back again when I let off throttle for a few secs. I have experienced this withholder chysler minivans and it was a lack of vacuum to a/c control head under load. I found my windsport has a vacuum cannister and it seems to hold vacuum,no obvious leaks found. has anyone else had this issue?
When the engine is not producing sufficient vacuum, the vacuum canister must supply the needed vacuum as you stated, There must be a vacuum leak in the system that the canister can not overcome. You can isolate each component in the system and using a hand held vacuum pump test each component. Usually you will find a split in a vacuum line where it connects to a component.
Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow