I got a 03 F150 with a 5.4 v8 and 4R70W. When I give it gas (accel) the a/c goes from the panal to the windsheild defrost area. I also have a problem with the shift on the fly four wheel drive not working all the time. This makes me think it is a vac problems since, both of these use vac to work. How do you track down a vac leak on these damn trucks? It has about 100 vac lines and the dealership aka stealership said there was no vac leak but never put a vac guage on it to test it. SO where do I start?