Howdy fellow Subaru folks,

 

I just bought my first "new gen" Subaru, a '92 Legacy sedan 5 speed. Definately an upgrade from the '86 GL10 in terms of handling, power not so much. Anyway I have this problem where when I push a heater control button while driving steadily down the road, I feel a sudden jerk, like the ignition is cutting out momentarily. It doesn't seem to matter what button I push or how many times. Has anyone else had this problem? The heater seems to work OK.

Any chance you're pushing the "Defrost" button? And your car has A/C?

 

That jerk could be the A/C compressor switching on to dry the air and clear your windscreen.

 

I've found that keeping the belt tension on the compressor within specs gives the most smooth transition between A/C on and off.