well, you can alter your setup and enable separate control over the water valve. The vacuum solenoid I found is supposed to be a 12v solenoid that will create the vacuum needed to switch the water valve on and off. So, you put the solenoid under your dash and a power switch on your dash and you can turn off/on the water at will completely independent of your a/c controls. This way, if you want to blend in warm air you can turn off the water valve and have the normal operation and control of your temperature. Allows it to work (or not) with vent, norm, or max setting.
I just never liked the all or nothing result of this mod. I also dont like cutting into my air conditioner lines.