Thanks for the Cross post. I might not have found this thread otherwise. Between your post and the following I think I understand possible causes.
Thanks for your detailed repair procedure. I haven't looked at the car yet, but it sounds like this is doable.
My question is: Is this a real HW problem or is the ECU looking for a certain feedback signal on the control circuit (or position sending potentiometer) when it adjusts the valve and the aged valve is just responding slowly ... possibly because of some interaction from the preconditioning and the EVSE being pulled quickly.
This referenced page <https://www.autocodes.com/p1f56_chevrolet.html> gives the detail that the ECU "... can drive the valve motor in a forward or reverse direction. One end position of the range is the Radiator connection, the middle position is the bypass position and the other end is the chiller position." This means the valve has 3 positions and the ECU must vary or pulse the signal to get the valve in the desired position.
And, in the other thread, Tim provided valve position feedback info (though I don't know the source of his "References") ...
The link at the end of Tim's post references back to this current thread.
Clearly multiple people are seeing this problem; But it is intermittent. I do precondition somewhat often so I can see how that might correlate with what others are experiencing.
@evfix : What was the condition of the valve (and position sender) that you removed from the vehicle?
Thanks ya all!
{I've got 3 vehicles and 2 boats I'm maintaining so I'm not ready to jump into another repair if I don't need to.}
