Heater blowing cold

[Ryej2003]

2003 explorer xlt 4.6.. blend door actuator isnt clicking so i ruled that out. not sure if it could be the heater control valve because im not familiar with the open and closed position, but it is not moving when I manually turn from hot to cold. Heater core hoses are both hot, not burning hot , but hot. Cooland level is normal. What else should i check? Im running out of ideas.. please help!!

 

[Donystoy]

I think these water valves are normally open meaning that they require vacuum to close them. With this in mind I wonder if you have an air lock in the system. I just replaced mine this week as the original one had a corroded bushing where the actuator arm attaches to the ball in the valve body. This would only cause me issues with too much heat when air conditioning was required. I only found it when I had the air intake removed to clean the throttle body. I noticed the arm on the valve hanging loose.
When I installed the new valve I also installed a "flush port" higher up in the hose only to allow me to remove air as I am planning on changing the anti-freeze.
Another possibility is that your water valve could be seized in one position. If you have a small hose you could remove the system vacuum tube from the valve and attach the hose to it. Putting the other end in your mouth you should be able to get it to operate. I just did this to verify the operation of my EGR valve.
The system rubber elbow that attaches to the vacuum port on the water valve was very loose on mine necessitating me to put a wire around it to make it snug. You might have the same issue.