Ok, here's a crazy idea. I want to do the max ac mod seen but with a twist. Instead of linking the vacuum hose to the max ac switch, why not activate it from a 12 volt switch on the dash?

Reason to do it this way: where we live there is cool in the morning warm in the afternoon cool in the evening weather all the time. It's rarely warm enough for max a/c ... in fact usually the vent will do fine as long as warm air from the core isn't bleeding through. That was my original problem ... the vent air is warmer than outside. The blend door works and seems to seal, but I'm told the leak a lot. I could do a ball valve under the hood but in the fall here it would be on in the morning off in the afternoon, on in the evening. Often when the sun goes down the temperature drops some 15 degrees or more.

So the idea is to tap into the power behind the HVAC controls to get 12 volts, have a radio shack switch on the dash control any old vacuum switching valve (say for instance this one and have that activate the heater heater valve from the max ac mod.

But then I got to thinking, why have the vacuum switching valve in the loop? Why not use a solenoid heater valve like this one? This guy could be controlled from the dash and would be a lot cheaper. There will be some plumbing issues, of course. Is there a pressure problem maybe? Should I do the more complicated several parts, or can I use any old solenoid valve?

Any thoughts on this?

 

There is a site which has a kit that does just, that as well as some other things like keep it closed in defrost position as well.