The vacuum valve only stops water flow, so if it is bypassed the heater will still work. Looks like the manual valve someone added is in the “open“ position, so that should not stop water flow.
Yes I bought the car in Arizona so they had the manual heater valve closed. I opened it. One more question. I have factory AC. Do I have to remove the incide AC vent below the dash to get to the heater box?
