In my '97 Ram Van 2500, why does engaging the defroster seem to be activating the AC? I noticed that using the defroster causes the freon pipe to be stone cold & causes much condensation to drip off from the AC "box." When I use the heater, the AC gear doesn't get engaged; I thought the defroster would just be the heater gear pointed up to the front glass.
Ultimately, I'm trying to troubleshoot an overheating problem.