MPG gain - AC bypass

[8thTon]

I so much prefer manual controls, where I can pick the outlet, recirculation, fan speed, temp and AC. Ford hasn’t done that in forever though. I guess they assume people are to dumb to figure it, and maybe they’re right.

 

[RonD]

It all started with automatic transmissions......................and it will end at MANDATORY self driving cars and trucks

 

[engine]

Thanks for the good discussion. It was very educational as I was listening in and helps explain why the HVAC does what it does when it is working as it is supposed to. There is a lot behind that deceptively simple control knob!

 

[cbxer55]

It all started with automatic transmissions......................and it will end at MANDATORY self driving cars and trucks

Teslas? Let us all pray that doesn't happen!!

 

[gw33gp]

Thanks for all the tips. It has been a while since I studied the vacuum routing for the HVAC controls. I was pretty sure I could make it work like I wanted by putting a valve system in the lines. I didn't experiment with it to see if it would work. I thought the heater core for the blend door always had hot coolant flowing through it and that was bypassed in Max A/C. If hot coolant is shut off in Max A/C, I may have to rethink what I need to do.

I have a Ford repair manual with wiring and vacuum diagrams for the 2002 Ranger. Hopefully they are correct. I will study everything to see what it takes to make it work like I want it to. Hopefully it can be done with the control switch. That would make things easier than having to switch a valve or valves when I want to use Max A/C.

Now that I am thinking about it more, I think what I decided would work the best was to have the door the for outside air intake close when in normal A/C instead of making it work like I want in Max A/C, but I don't remember if I came up with a way to do it. I will post if I find a way to do what I want, whatever it is.

As I recall with my 89 STX, all I had to do was switch to 'recirculate air' when off-road. The A/C still worked normally but was not pulling in outside air. I think I could use that recirculate feature on any HVAC setting.

 

[RonD]

Yes, earlier systems had a manual fresh/recirculate vent option

As said just unplug the grey vacuum line from the by-pass valve in the engine bay, and plug it
Then test in MAX AC to see if you can adjust the Temp, you should be able to since coolant is still flowing thru the heater core
And in COLD setting it should still be pretty cold assuming AC system is OK
It would be the same as regular AC but using recirculated air because outside air vent is closed

So done, and doner, lol

 

[Dirtman]

This thread makes my brain hurt.