1991 Loyale wagon, EA82, 5-sp manual w the 4WD button in top of the stick. About a month ago it would no longer go into 4WD, and about the same time the hvac system would no longer direct air to defrost or to heat (feet) - only comes out through the panel vents.

 

Are these pneumatically controlled? When working, there was a slight "whoosh" whenever any of these was engaged (4WD and hvac selections "defrost", "heat", etc.) that suggests pneumatic operation.

 

Any suggestions on how to fix these issues?

 

Another issue is it seems the air conditioner compressor is running although not engaged. Not sure if it's related.

 

Those are both vacuum operated. There's a vacuum canister on the passenger side near the strut tower, there's a "T" fitting near that, with one vacuum line running to the engine. That's probably come loose.