my 08 mercury grand marquis is overheating at idle or park with heater on, not overheating driving down the road, overheated twice,after first time i replaced the thermostat,overheated again, at popeyes drivethrough,heater on, checked fan relay for power,has it, also checked cooling fan plug at module leading to cooling fan, fan works, unplugged connector at other ind of module fan works going through module, fan just doesnt come on while driving, or idle with ac on,and when ac is on, engines revs up and down and almost dies, freon readings is off the chart high, blowing warm at idle im thinking coolant temp sensor, and think i have to remove alternator to replace it, just not sure if i have one or 2 sensors and google not showing me squat