I've had my 2012 RAM Crew Cab only for a little over one month and 1100 miles but I've noticed my A/C compressor engages every 20 seconds or so even when the climate control is in manual mode and set to floor heat. According to the owners manual, it should only engage when the controls are set to defrost, bi-level, or air conditioning. The compressor can also cycle as needed when the climate control is set to Automatic.
Has anyone else noticed this with their trucks? I don't know if this is affecting my mpg but the best I've been able to achieve in the short time I've owned it has been 14.1 on mostly highway driving with just me in it. I anticipate the mpg going up some with some more miles on it.
I've got the 3.55 gear ratio and the 5.7 of course. Thanks for any replies.

 

Is it set to just floor or floor/def? My 08 does not run the compressor on floor only, but i have manual controls and they may have changed things on the 09 up. Those 3.55 gears hurt more than they help if you have 20" wheels. I have 3.92's and only turn 2000rpm @ 70mph.

 

You may have a point there lxman1. I do have the 20's with the 3.55 ratio so I may not be able to get any better mileage than what I've seen so far. My thought process was to go with the lower ratio since I don't tow anything heavy and get better economy but I may have made a bad decision there. As far as the compressor issue, it cycles on when I have the controls set to manual and in the floor hear position, no defrost or bi-level so something may be malfunctioning. On two occasions, when pulling into my neighborhood at around 15mph, the compressor has engaged so harshly, the truck lurched forward like I had stepped on the brake pretty hard. That was accompanied by a loud ratcheting sound from under the hood for about 2 seconds. I'm definitely going to ask the Dealer to take a good look at that compressor.
Thanks for the reply.