Hi All,

I cannot seem to find the problem with my 380SL ventilation system. Here's the symptoms:

1. When the temp wheel is set to 'coldest', I get cold air, no problem
2. When I turn the wheel one click off of the 'coldest' setting the heat comes on full, no tepid, or warm, full hot.
3. The airflow is coming through all vents regardless of the setting/buttons I push on the ventilation control panel.

What I have checked so far:

1. I've removed and cleaned the temperature rehostat, it's showing gradual changes when connected to an ohmeter and I move the wheel
2. I've pulled the glovebox and turned on the vent system and did see the fresh air flaps open/close when I change settings on the vent control panel, so it seems that I'm getting vacuum to the system.
3. I removed the temperature regulator box, pulled the circuit board and re-soldered all joints on the board.
4. I replaced the monovalve and event checked to make sure it's working by disconnecting the power plug and it does allow hot air into the car when the rehostat is on full cold setting. When power plug is reattached, the coldeset setting goes back to just cold air.

I don't know where to troubleshoot next. Does anyone have any suggestions/insights? Since there is no redirection of airflow between floor/dash/defrost on any of the settings, is there some dampers I can check? When the temp wheel is set to 'warm' is there a control that regulates the hot/cold air mix somewhere?

Thanks in advance, Bob

 

Does anyone know where I can get a Monovalve for my 1985 380 SL part number 0008303484 also I need 2 pressure regulators #0280161012 or 0000780692. thanks