air conditioning

[stevenwagner06]

so anytime when i have my air on vent or a.c. or max a.c. and i am accelerating the air goes from vent to defrost and then when i let off the gas the air goes back to vent so


acceleration or strain on motor= air moving from vent to defrost


any ideas?????

 

[Gus Gorilla]

Steven,
What you are experiencing is a loss of vacuum and it's normal. When the HVAC system loses vacuum it will default to defrost. The thinking being that you could drive in any condition with only defrost. With the throttle plate closed or close to closed the engine makes a good amount of vacuum, the HVAC uses it to control the air mode doors. When the throttle plates are opened up for full or near full throttle the vacuum is almost completely lost, so the mode door defaults to defrost. Don't sweat it.

 

[stevenwagner06]

yea my moms has that on her mustang but it is doing it too much, for instance say im going down the free way at 75 mph at about 2500 or 3000 rpm it routs to the defrost i dont think its normal cuz it does it when im just cruising not flooring it at higher speeds

 

[KPT]

Its not normal. Check all the lines to the vacuum reservoir. Second gens have a ball near the airbox, I'm guessing first gens have something similar.

 

[Gus Gorilla]

Yeah, KPT is right. In that instance it isn't normal. Start checking for leaks. If you have a vacuum hand pump and some golf tees you can isolate components and lines, apply vacuum and check that way. Much easier than chasing them all out.