Larry- If I have to much to much oil in the system would it affect the vent temp?

When I ran the test the heater hoses were hot so I used a hose tool and pinched off the supply hose to the heater with no drop in vent temp. should they be hot? Maybe pinching off one hose is ineffective. Does our car blend air with a door or by cycling the monovalve?

How do you tell if the monovalve is working?

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87' 300sdl