Hi, i have a 2005 Mitusibishi eclipse gt. the car runs great, just the only thing i have notice now that its going into winter is that when the defrost is on, and the car is at idle (such as when i come to a stoplight) the car idels down to around 500 RPM and the car shakes. i belive the shaking is due to the low idle speed. but i was wondering if anybody knew what would be causing this?

 

Hi, the reason your car is idling slower and rougher when the defroster is on is because on defrost, the system cycles the A/C compressor. It's designed to do this to keep the seals in the compressor lubed through winter so you don't blow the seals when you fire up the A/C in summer.