hmm, I took it apart and the valve and the rubber seals all look to be in fine shape....if they were damaged, that would cause it to not seal off the passage and cause heat when you didn't want it.
The original problem was that it was not heating.
I also see that the valve when at "rest" makes the coolant passage open so that water flows to the heater core...so why it continues to heat when it has 12v and ground when the wheel is at "max" makes absolutely no sense to me...not to mention that its getting ground when on "max".

So I'm assuming now its not the valve at all but something else, either the temp control unit or the temp sensor. If it were the valve I'd be getting heat when I didn't want it, it would appear as the valve could not seal off the passage of the coolant to the heater core if it were bad.

BTW, if it matters, the heat is coming out of the center vents only. The sides and floor are not blowing anything.

Thanks for all of your help thus far.

__________________
Rob

'87 560SL
'87 Buick Grand National
'79, '89', 99' Anniversary Trans Ams