No Heat on 1990 190E 2.6
 

I'm getting Heat out the side vents when I'm going uphill on passes, then on the downhill side getting cool air. A/C was just fixed and recharged, but now isn't coming on, was working good on the trip until the heat started coming out the side vents. Climate wheel was set low....outside temp was in the 80's. Could this be a monovale or some relay that has gone out?

It sounds like a vacuum leak. You loose vacuum when going uphill and the no-vacuum default (all actuators in their relaxed position) is heat and defrost on.

Happy hunting:rolleyes:

Thanks Jim! I'll have that checked out.

Check for bad vacuum line connectors in the area right around and above the brake booster. Often these get hard and brittle. If you need more line, take a piece to an autoparts store and match it up.

Keep us posted,

Haasman