Air Recirculate Switch Not Working
 

The air recirculate switch in my 86 951 isn't working. When you push it, the light comes on, but it doesn't shut off outside air.

With summer approaching, I'd like to get this working so the a/c doesn't have to always pull hot outside air. Does anybody know how this works and what might be wrong?

Anybody have some thoughts on this?

No clude here. Mine make a nice little humming noise when engaged.