[rattlsnak]

FIL has a 2000 merc grand marquis and has a problem with the Electronic Automatic Temperature Control. When put on 65 it blows cold, when put on 68 or higher blows hot. So it's either full cold or full hot, no in between. This leads me to believe that the blend air door is working, just not being controlled properly? I ran the eatc self diagnostics and the unit has no fault codes so I'm leaning towards the control head itself. Anybody have any exp. with these?