Originally Posted by Viva
My brain is straining to remember why (or if) there was a reason that a "simple' bypass wasn't supposed to work, but I can't remember. So maybe there wasn't any reason
Viva you're not a bit dense, all this discussion with variations how your goal can be met does sound complex
mostly because you've not yet done any work with Ford's HVAC control system.
While I didn't dig too deeply into the Max Air and Cold Rush offerings I could instantly tell from their images of the kits it could be greatly simplified. My solution does what you need and in the most simple, uncomplicated and relatively inexpensive manner. Its added advantage is you'd have complete and independent control of hot coolant flow to your heater core regardless what function is set on the dashboard; Vent, Heat, Defrost, A/C or Max A/C.
As I said earlier most all vehicle systems had the heater control valve which we're going to replicate. There is no real conflict with any other power train or body system at all; think of this as we're going old skool on the heater system.
The "how" is simply inserting one valve in the front heater core loop which begins at the fitting just off the thermostat housing on the front of the engine, just under the alternator.
There is no reason a single shut off valve cannot work on its own. There's no impact or interference with any power train or body system other than the HVAC portion.
Our first decision is how we're control or operate this valve; vacuum or electric only. (Keep in mind this single valve will do nothing more than stop hot coolant flow to the heater core, just one the inlet side----nothing else.) Whether we use an already present vacuum signal or just an electrical signal to open/close the valve we need an unobtrusive & easily reachable interior switch. (I've found a suitable 12 VDC valve that greatly simplifies this---it requires only installation in the heater line and a suitable switch, its here: http://www.electricsolenoidvalves.co...alves-n-o.html
, the 12 VDC version.
Because that valve doesn't require integration into the vacuum system its just as simple as cutting the heater hose of choice, fitting the valve with suitable barbed hose fittings and clamp it in place. From there run one each power and ground wire and a switch to operate the valve---done.
The upside to this arrangement apart from its low cost and ease of installation is it would be independently controllable of any other HVAC function. Regardless where the Function Control is set (Heat, Vent, Defrost, A/C, Max A/C) you still have complete control of the valve. No additional vacuum hose, fittings or runs---one valve, one switch, some wire, in-line fuse holder, misc clamps cable ties etc--done.
The info we're contributing might make this seem far more complex than it is---that's due our different POV's or approaches to this. The common element is that single valve installed to interrupt hot coolant flow to the heater core, the only real differences is how we control that valve.
If you've ever successfully changed or replaced a heater hose and/or wired anything automotive your skills are in place---done.
We'll talk you through this I swear!!
Sorry to yammer on and repeat myself so often.