Modifying the fresh/recirc htr-a/c-defrost control

[Archive]

One thing I don't like about my truck ('97, I don't know if 98+'s are the same) is that I can't select between fresh and recirulating air on individual heat-a/c-defrost positions. I can't stand breathing the exhaust of some beater smog-pumper in front of me when I've got the defroster on or the heater in the "floor only" mode. If I turn the selector knob to the recirculating position, most of the air comes out the dash vents. My arms and chest get nice and warm while my feet are freezing. On a cold day, I'd rather have it blow on my feet, but in order to do that, I have no choice but to receive fresh (read: car exhaust) air only. I'm considering modifying the controls in order to be able to select between fresh and recirculating air regardless of what position the control knob is set at. I recently drove a rental Freightliner, and it had a fresh/recirc pneumatic push button next to the slide controls. I'm wondering if it's possible to add something like that, to control the "blend door" (I believe that's what DC calls it). The Freightliner of course, used compressed air for movement versus our trucks using vacuum.
Anybody have any opinions?
Thanks, Andy

 

[Archive]

Andy ,the way I beat is is just closeing the mid-level vents,works good for me.

------------------
95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[Archive]

One thing I don't like about my truck ('97, I don't know if 98+'s are the same) is that I can't select between fresh and recirulating air on individual heat-a/c-defrost positions... .
Anybody have any opinions?

Andy,
I don't have a solution yet, but I wanted to reply just in case DC is monitoring this board. I agree with you 200%, the A/C controls are one of the weak spots in our vehicles, and it shames me (and even more shame on DC) that they give us so little control. My wife's "shoebox" Geo Tracker is much better designed.
A "modern" system should have five distinct controls for the driver that work independently:
1) Fan speed, including an "off" position
2) Recirc / Outside air
3) Outlet control (floor, vent, windshield, and combos of these)
4) Compressor on/off
5) Temperature

I realize that the Compressor might have to be wired so that it won't come on unless your fan is at least on "low", but other than that there is no reason to not give the driver full control of his/her system. Those who can't read the owner's manual can ask their salesman how the system works!
One of my planned summer projects is to figure out how to wire my system differently, but I just can't see doing this now with it in the teen's outside.

 

[Archive]

I never like outside air, so, i just wired (read "bailing wired") the blend door shut. If you decide to do this, the trick to getting the glove box out is to open it, then put your left hand on the front (where the latch is) and your right hand on the back (the rear of the glovebox) and just push the back part. The back part of the glovebox is flexible and will bend, sucking the 2 side retainers in (dodge tech showed me that neat little trick).

-dm

------------------
'01 Eth 3500 dually, no mods planned except maybe an amsoil filter & guages. See My Truck and also be sure to read What tools & methods to use for an easy 1st oil change!!!
"Be happy you don't get all the government you pay for. " -W. C. Fields

 

[Archive]

Thanks guys. You know what else I'd like to see is an infinitely variable fan speed knob(like a rheostat) rather than just 3 speeds to pick from. Better than that, luxury cars have "Climate Control", why can't trucks have it, too? I'd gladly pay extra for that.
Andy

 

[Archive]

Have you thought about a vacuum switch. Isn't the fresh air/recirculation door operated by vacuum(actually operates the acuator) like the other doors in the ac/heat unit.

------------------
Bill Thomas
Missouri Mule - 96 Wht 4X4 ST CC,5 spd, 3. 54, 8 ft bed, 1 ft high cheater boards.
99 Freightliner bl/wht FL60 ISB-5. 9 24v,215 hp,520 tq,6 spd, 3. 59 nsr,16 ft box, 19. 5 tires,Wt/gvw 11,000/23000

 

[Archive]

Driving home from work tonight, I was just thinking, I might borrow from 1960's truck technology and rig up a push-pull cable control for the blend door. Not very high tech, but it would work!
Andy

 

[Archive]

Andy, the Blend door is operated by a bi-directional vac. motor. If you disconnect the open side hose and install a tee and hook both hoses to the close side then you would always get inside air. This would require a check valve in both lines, they used to be available. You might even run the hoses out near the glove box or somewhere so if you decided to get some outside air you could easily switch back. Just a thought. bg

------------------
White 99 3500, QC, 3:55, auto. most options except leather, Line-X bed liner, fiberglass running boards Rancho 9000s, bug shield and window vents, black vented 5th wheel tailgate, 100 gal. aux. fuel tank.

[This message has been edited by B. G. Smith (edited 01-04-2001). ]

 

[Archive]

On my brother-in-laws 97 Ram gasser, at least he has separate fan only and AC controls. I like his much much better. It has 3 dials. The top one sets the air outlet, dash, floor, defrost, blend, etc.
The middle on is the fan speed and AC selector. Straight up is off. Turn counter-clockwise and you choose AC and have four fan speeds. Turn clockwise (from straight up/off) and you choose fan only and have 4 fan speeds.
The bottom one is the temperature.

Leaving the blend door shut, to recirc only will make your windows fog up much more quickly and easily. I just primarily leave mine on vent or feet, unless it's hot, then it's AC(fresh air) or MAX AC (Recirc).

------------------
Y2K 2500 Cummins ETC/DEE, SLT+, 4X4, Quad, LB, Intense Blue Sport, 3. 54 LSD, rear aux. springs (camper special), sliding rear window, all options except cab clearance lights including agate leather, totally stock engine, silencer ring removed, "stealth," mod to run fogs with high beam. Since everybody else listed their toys, I will too.
1995 Kawasaki ZX6-R (For Sale)
1990 Toyota Celica
1983 Mazda RX-7 GSL (For sale)

 

[Archive]

Leaving the blend door shut, to recirc only will make your windows fog up much more quickly and easily.

Not if you have the a/c on, it will act as a dehumidifier.
B. G. Smith, thanks for the info.
Andy

 

[Archive]

Andy, you may want to verify which type you have... mine is not push/pull, it is just pull with a spring loaded "push".

-dm

 

[Archive]

This has long been one of my complaints about U. S. vehicles. The ventilation controls are seriously lame. Jap vehicles have great controls compared to ours.

 

[Archive]

Originally posted by Andy Perreault:
Thanks guys. You know what else I'd like to see is an infinitely variable fan speed knob(like a rheostat) rather than just 3 speeds to pick from. Better than that, luxury cars have "Climate Control", why can't trucks have it, too? I'd gladly pay extra for that.
Andy

It kinda frosted me (pun intended) that my 89 LeBaron has climate control, but my 11 years newer, $20k more expensive truck with more space under the dash doesn't have a climate module.



------------------
Y2K 2500 QC Sport 4x4 LWB
72 Dart 340
89 LeBaron GTC 2. 2 TI

 

[Archive]

Last year I was messing around with an electric heater (AC) in the cab so it would warm up. I used a household AC thermostat to control a setpoint. In the end I gave up on the project as the AC was too expensive which justified the ESPAR...

But, I've often wondered about using the same electric heat thermostat or a newer digital version to control the blower on our trucks. I. E. climate control. .

Anyone try this??

 

[Archive]

Andy P - With the blend door shut (to recirc only) it will TEND to fog up inside easier and more frequently. You are right that the AC will act as a dehumidifier, and it will probably always defeat the fog. But my key word there is TEND. #ad