How do I keep the motor running?

Being green sucks! I would talk to your local Ford/Mercury dealer to find out what the proper operating mode is.

The engine will continue to run if this things happen, the AC button is pressed and the Econ is not active but AC does not work when the temp is lower than 60 F due the maximum cold the AC system can deliver is 60f ,......IN WINTER, when the temps are reversed and you need heat from the car, you need to press the DEFROST BUTTONS to keep the engine running continuously. my best selection to get max heat from the My 2008 Mariner is DEFROST/FEET HEAT BUTTON and RE-CIRCLE AIR.. Additionally I block some Air flow putting a piece of thick Cardboard in front of the Radiator and between the AC radiator (Middle of 2 radiators) I ONLY BLOCK 1/2 of the radiator air flow, normally the half that is closer to the coolant reservoirs, this makes my Mariner heat up faster and sustain the temp more stable in winter, then I REMOVE the cardboard in spring, I Feel your pain i live in Chicago and as you may know the temperatures can go pretty low, FYI I'm NOT LIABLE IF YOU DO SOMETHING WRONG I'M NOT RECOMMENDING YOU DO BLOCK YOUR RADIATOR I'M SIMPLY STATING WHAT I DO IN WINTER Good luck !!