I have what I believe to be a vaccuum line leak in my air conditioning system. It is a 99 F150 with 5.4 motor. The air stops blowing and/or switches to defrost on hard acceleration or climbing a hill. I know I'm supposed to be looking on the passenger side behind the battery. I see many wires/hoses/lines in this general area and am not 100% sure what I'm supposed to be looking for. Any help would be greatly appreciated.