'85 300D heat driver's side cold passenger

Hot air is coming out of the appropriate places on drivers side, but ambient temp air from the passenger side. Buttons on dash change air routing but still temps remain as above. I have the automatic climate control. Both hoses of the monovalve are hot. Any suggestions. Days of internet searching have come up empty. 1985 300 D eurodelivery model 280,000 mi.

Thanks,

Paul Sipe

Forums

Chassis Model Number