I have no heat, replaced leaky water pump and thermostat, also thermostat housing. Found leak in heater return hose and replaced both heater hoses. Checked heater circulation pump, all good. Checked H.C.V., flushed and electrically operated although moves very little internally; never got flow through the two lower hose connections, both upper hose connections are wide open. Checked both in-line check-valves, all good. Flushed system until clear. Checked cabin vents, still cold air and plenty of it. How should the HCV function, should the inlets/outlets clearly open/close?

 

Also looking for info on the heater valve and the action. Does 12V set for heating? When is 12v applied? On mine it seems to have 12V almost all the time although at one point i thought i was getting 6v.

Heat was low, aux pump good. Applying 12v makes it click but have not yet removed to see if it is stuck . With 12V plug off, i am getting good heart now.

 

12 volts closes the valve to the heater and recirculates.