MPG gain - AC bypass

[Dirtman]

Wear better socks...

 

[RonD]

Yes, I hear goat hair socks are the warmest

 

[RegularGuy]

In my case, I hold a particular distain for air being blown directly on me and prefer to use defrost where most individuals would use floor/front vents... So for me, the AC is almost always on. Combine this with lots of short trips and the compressor is getting things to temperature for the better part of my drive...

I particularly like that way that switch was taped, simple, revertable, basically free, my kind of mod. I appreciate the insight! I've never found major issue in the Northwest regarding cabin moisture, regardless of vehicle. The only thing the Ranger feels to be lacking for me though, compared to other vehicles is circulation control. It would be nice to have a choice, I've felt particularly spoiled even by my Subaru which allows me to draw outside ambient air without the fan being on.

 

[cbxer55]

It depends on your driving habits. I rarely use the AC and drive with the windows open, so it's just wasting power for nothing. And I still have the full factory clutch fan air capacity.

Same here. The ac hasn't worked in my Ranger for years. No smell I can detect in mine after 22 years. I don't use the ac in my Mustang or Lightning either. With the exception of the Mustang, which came with a sparky fan, I refuse to use them. I tried putting one in my Lightning in 2019, it went up in smoke the first time it turned on. Never again!!

 

[8thTon]

Same here. The ac hasn't worked in my Ranger for years. No smell I can detect in mine after 22 years. I don't use the ac in my Mustang or Lightning either. With the exception of the Mustang, which acme wit ha parky fan, I refuse to use them. I tried putting one in my Lightning in 2019, it went up in smoke the first time it turned on. Never again!!

I know a lot of folks like AC and it's pretty much on all the time except for winter, but I just don't like it unless it damned hot out and I'm stuck in some urban heat island. My Ranger has a refrigerant leak that I can't find and quit last year. I'm going to make one more attempt to fix it, just because it bugs me that it doesn't work, and then to heck with it.

 

[gw33gp]

It was posted elsewhere, so I'll copy an abridged version here:

The wiring diagrams are likely correct in terms of point-to-point wiring, but what is shown withing the boxes representing switches and other devices is best considered an artistic rendering. It's not always useful for troubleshooting. Mine is a 2004, and I have diagrams for 2002, 2005 and 2008. The 2002 and 2005 don't show the floor/vent position at all and the 2008 shows the AC engaged for all modes but "off". So I pulled mine apart.

On my 2004 the AC clutch is energized for both AC and DEFROST modes, as well as FLOOR/VENT. It is off for FLOOR and VENT, as well as OFF. I thought about disabling the AC for the FLOOR/DEFROST mode but decided to leave that alone, and just disabled it on the FLOOR/VENT mode. Taking the HVAC unit out was pretty easy, but taking the mode control out is not for the faint of heart. Note the detent spring and ball behind it that can easily get lost. Also, there is a sliding vacuum control valve moved by the gear, and that must be phased properly on reassembly.

To disable the AC on FLOOR/VENT I cleaned off that one spar with brake clean and applied some thin Kapton tape over it. That is a tough resistive tape with a good adhesive used in electronics manufacturing, which was suitable for this, but there are probably other tapes or ways to insulate it. Now when the wiper hits that spot it will not make contact and the AC won't turn on. I reapplied some silicone grease and put it back together - had to replace a bulb too. Everything worked well. Since I use FLOOR/VENT and FLOOR most often I'm hoping I may see some mileage improvement.

8thTon, Since you have taken this switch apart and are familiar with it, maybe you can advise on another issue. I would like to be able to control the temperature when in Max A/C position. As is, when in Max A/C, the temp controller does not function.

You might say, so what. When I am off-road with a group, a lot of dust is kicked up and I switch to Max A/C so that dust is not pulled into the cab. Unfortunately, it usually gets too cold and I have to cycle between Max A/C and Off frequently manually to keep from getting too cold or hot.

I have looked at installing a valve in the vacuum line system that would allow the temperature controller to operate when in Max A/C while still recirculating cabin air. If I could do something in the switch to make that happen, I would like that better. I have a spare switch and could take it apart to experiment with it. Do you think what I want to do would be possible by modifying the switch?

 

[RonD]

The MAX AC setting closes the fresh air vent using a Vacuum motor, so its a mechanical selection on that rotary switch, it also cuts coolant flow thru heater core, so temp control wouldn't really work in any case
You could unplug the grey vacuum hose on the coolant by-pass valve in engine bay, and plug it, and see if temp control was working, heater core still hot, but not sure if Blend Door is disabled in MAX AC?

You could use an EVAP or EGR solenoid and a switch to apply vacuum to that vacuum motor to close the fresh air vent in any setting, you can access vacuum lines needed by folding down glove box, there is a vacuum manifold there, looks like wiring but its vacuum hoses
You could activate the added solenoid via the AC demand signal in 2002, so it would be automatic in AC or AC Max both

 

[8thTon]

8thTon, Since you have taken this switch apart and are familiar with it, maybe you can advise on another issue. I would like to be able to control the temperature when in Max A/C position. As is, when in Max A/C, the temp controller does not function.

You might say, so what. When I am off-road with a group, a lot of dust is kicked up and I switch to Max A/C so that dust is not pulled into the cab. Unfortunately, it usually gets too cold and I have to cycle between Max A/C and Off frequently manually to keep from getting too cold or hot.

I have looked at installing a valve in the vacuum line system that would allow the temperature controller to operate when in Max A/C while still recirculating cabin air. If I could do something in the switch to make that happen, I would like that better. I have a spare switch and could take it apart to experiment with it. Do you think what I want to do would be possible by modifying the switch?

Unfortunately it's been a while since I had that apart, and I was not looking at it from that perspective. I believe the temperature blend door actuator is an electric motor on my 2004, but some of the diagrams had errors and I believe the control system changed over the years. You'd have to see how yours works. If the temp control is electric then it's just disabling this in the control switch - you'd have to take a switch apart and see how the temperature control circuit is routed when its in the MaxAC position, which I wasn't looking at. The wiring diagram I have does not show this, but it is also not complete/correct.

 

[RonD]

I don't see a wiring connection between Blend Door motor and AC selector, so temp control should still work IF heater core is still getting hot coolant

 

[8thTon]

I don't see a wiring connection between Blend Door motor and AC selector, so temp control should still work IF heater core is still getting hot coolant

There is one on the wiring diagram I have for a 2008, but not the one for my 2004 - the problem is that my 2004 actually has the same setup shown for 2008. Apparently they just didn't get around to updating the drawings for a few years!

The blend door motor is toward the lower right:

 

[RonD]

No connection, just has the 3 variable resistor wires from temp control knob
And a 12v and ground wire
So should work the same in any setting on the AC control
Looks like the same wiring back to 1995 when Blend door went electric

Try disabling the Grey vacuum line on Heater hose by-pass, and see if it allows you to warm up the air in MAX AC

 

[8thTon]

No connection, just has the 3 variable resistor wires from temp control knob
And a 12v and ground wire
So should work the same in any setting on the AC control
Looks like the same wiring back to 1995 when Blend door went electric

Try disabling the Grey vacuum line on Heater hose by-pass, and see if it allows you to warm up the air in MAX AC

I know that is what it shows, but don't take it too seriously. I have found that these wiring diagrams are decently correct when it comes to the connections between devices - the harness essentially - but what is shown within the devices is conceptual at best. And often simply wrong. I don't know if it does or doesn't disable the temp control on Max AC, but I would not be surprised. That's the intention of the setting.

 

[RonD]

Well it would also have to change the Blend Door position to block heater core air flow, or wouldn't be much point in disabling it if temp setting was already on Cold

MAX AC closes fresh air vent and by-passes heater core coolant flow, that its difference from AC
By-passing heater core flow would make the Blend door moot since that its only reason to be there, to direct air thru or away from heater core

So I am betting its not disabled, but lack of heater core coolant flow means temp wouldn't change in MAX AC because all there is, is AC, no Heat

 

[8thTon]

Well it would also have to change the Blend Door position to block heater core air flow, or wouldn't be much point in disabling it if temp setting was already on Cold

MAX AC closes fresh air vent and by-passes heater core coolant flow, that its difference from AC
By-passing heater core flow would make the Blend door moot since that its only reason to be there, to direct air thru or away from heater core

So I am betting its not disabled, but lack of heater core coolant flow means temp wouldn't change in MAX AC because all there is, is AC, no Heat

Perhaps - I cannot tell what the control system is doing. If it's just shutting off the vacuum to the bypass motor that would be part of the rectangular vacuum valve shown here - you'd have to figure out the control scheme for that particular vacuum passage:

 

[RonD]

I don't think you would need to dig into that vacuum router to get what gw33gp wanted, a way to close off outside air vent in dusty situations without freezing in the cab, lol

Here is a diagram of the cab vacuum motor/vents and control router: https://www.explorerforum.com/forums/attachments/hvac-20diag-gif.41768/

At the far right is the Water Valve vacuum motor, that's the one in the engine bay that shuts off heater core flow, only used in MAX AC, just like the outside air vent is only closed in MAX AC
However it does show vacuum at both in OFF setting, but not sure that's helpful since fan would be powered OFF as well