
Hummmnnn Well not real sure you got it fixed. Reversing the hoses (air lines) will not keep the valve from being energized. If it is hot to the touch, that may indicate power is being applied as you suggested.
Sounds like you either had a bad switch which kept power applied, or a short or some sort. Short would have to be on the negative side going to the valve as positive side is not switched.
So did you reverse the hoses (air lines), the power connections, or both?
Did cleaning the mac valve cure the operational problem and does it now work with the switch? Hope so.