The heater/AC control on my '94 LY is out of an early '80's K-car. The buttons work, as does the slide to select temperature. However, if you look at the way this control is made, when the slide is in the "cold" position, the mechanism presses a button which activates a vacuum line. That line is attached to a valve inline with the heater core intake, to shut the flow of engine coolant to the heater core, as the air conditioner is made operational.
So here is the issue I have. That vacuum line is either blocked or kinked somewhere (it snakes from under the dash on the driver's side to the hose feeding the inlet to the heater core outside the firewall on the passenger side) so that it does not activate the shut-off valve. Added to that, the mount of the actual valve on the mechanism seems broken and flops around, so it isn't worth the cost of yanking it out and replacing it.
As a fix, the vacuum-controlled valve was removed and a manual one put in in its place. That works just fine, but means that when I need to switch from air conditioning to heat or vice versa, I have to stop, open the hood, and manually open or shut the valve.
What I am looking for is either a 12-vdc solenoid-activated inline valve (so I can put a switch on the dash to open and shut the valve) or an equivalent "switch" that would use the existing vacuum-activated valve.
1987 Excella 32-foot
1999 Dodge Ram 2500HD Diesel