This is hard to explain but i need to find out what is is so i can fix it. When i have the heat or a/c on.... For example when it is on all feet or all vents it will automatically switch to defrost and then when i punch the gas and then immediately let off it will come back to the feet or vents i think it is a vacuum hose but which one i'm not sure which can anyone help

 

Dam thats weird I have never heard of that before hopefully someone can help you

 

Letting off the gas generates a high vacuum in the system. You've got a small leak ... look for cracked or brittle hoses or a loose vacuum line. The chances of it being a connection actually off is is pretty small.

 

Replace your check valves.

 

With my truck, if you hit the gas really hard, it will switch over to defrost but when you let off it goes right back... My old car did the same thing.

 

Diesel Demon is correct...there is a check valve in the system to stop that...change that.
I also added one to isolate the heater from the rest of the system on that line.

 

Where is the check valve located??

 

And what do they cost and do i get one

 

I believe the check valve to which they refer is, from the fan belt facing forward, directy backwards and to the right of the distributor. Trace the line back from the cruise control/ vent controltee

 

I had my AC rebuilt and it did the same thing it was a valve teethat the vacum lines connect to there's a little metal flap that got stuck when it gets dirty I blow air into it and fixed it till it got dirty again so I replaced it with a new one problem solved.