I have a 1999 Explorer. I can't get the A/C to blow cold at all. The heater is nice and warm though. BUT...when I have either one on, the truck tries to lurch forward every few seconds. The rpm's increase and then go back down...rinse and repeat. I explored it a little more today, and it seems that it only happens if it is not set to blow on ONLY your face, or ONLY your feet. If the blower is set to those two, it seems to run fine. Any other setting, and it lurches. Including A/C, MAX A/C, defrost, or any mix in between. Can anyone help me out here? Thanks a lot!