My 91 Legacy is acting up. Hot or cold, when I push the vent button on the air control, the engine idle becomes erratic. If I come to a stop after driving awhile, the engine sometimes idles down and out. When I push the A/C button, no problem. As soon as I turn off the A/C and go back to Vent, the problem reoccurs. I am pretty sure this is a vacuum problem, but the only vacuum lines I'm familiar with are the two on the intake manifold. I have looked at previous posts about an air canister for the air condioner controls, but would like a few more details. I bet my son lunch that I could get an answer from this forum faster than he could from his mechanic (non-Subaru) friends. Any help out there???

Bump

 

This is a little self-serving.

 

My 94 Legacy wagon (AWD, 5 speed) has developed a lurch when the AC is on. It is intermittent. It is pretty extreme and seems to more than just a compressor kicking in though.

 

thanks - Mark