I90E Heater valve (monovalve test)
 

1987 2.3 16v.

Its wide open and heat is pouring into the cabin. I would like to test if its the valve or lack of vacume on the line before I order another valve. What buttons should I push in the cabin to command heat (vacuum) from the red line?

Rookie question but the car is new to me and no manual etc. Hey at least I used the search function and found the source of Pompei! I just tie wrapped it off in the mean time.....94 deg outside today.

Thanks

When I had that problem it was a lack of vacuum due to a defective defroster pod behind the dash. I put a solid vacuum source at the valve to keep it closed until I replaced the pod.

I had to perform a vacuum test of the cross over valves that are located under the glove box on the right side to isolate the defective pod.

With the heat off, there should be vacuum on the red line going to the valve.

OK, so vacuum is on to the monovalve (to keep it closed) with heat switch OFF. The vacuum line runs across to the drivers side under the front wiper. Ill try to locate where it goes next. Thanks for the reply!

There is no monovalve in a 190E.

You're talking about a heater valve. In the 190E it is vacuum actuated. A "monovalve" is, on the other models (w123, w124, w126), electric powered.

My bad. It is referred as a monovalve here sometimes. Heater valve it is.

The arrow on the Heater Valve is pointed towards the engine. I understand it is installed backwards as the arrow should point towards the flow of coolant?