I replaced the monovalve in my 85 300SD and now have lots of heat. Unfortunately it all blows on the windshield.

I checked the vacuum and it's fine. The system retains vacuum and the gauge does not even twitch when I press the different buttons until I press the Off button. Then vacuum drops to zero and slowly creeps up again.

Test done with engine idling and vacuum gauge attached next to heater vacuum source under hood. By disconnecting blue vacuum line and attaching it to the gauge.

I have searched the diesel section (twice) and the tech section as well.

Up until a few weeks ago I could hear the vacuum doors thunking under the dash, now no sounds.

Anyone know how to make the heat blow on the floor? Is it the vacuum control panel?

Anybody?

Defrost is the default if nothing else works. You are not getting vacuum to the pod that directs air flow elsewhere or the rubber diaphrams are cracked within the pods.

If you remove the right cover of the center console, you will see a row of vacuum relays. These switch vacuum to the different pods. You can use a gauge to check vacuum input to the stack and then from each relay. This is how you can determine which pod needs to be overhauled. You can buy the replacement inserts from here

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)