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Modifications to Climate Control

Modifications to Climate Control

Tony Gardner & Gregory Andrachuk (Fresh Air for SIII), Shawn Mantoszko (Fresh Air for SII) & John Napoli (Compressor Control for SIII)

Tony Gardner Adds Fresh Air Control to the SIII

I have discovered how to obtain fresh air ventilation on my 86 XJ6 SIII and it may well be applicable to other models with a similar system. This modification gives the option of having the forward motion of the car push outside air (hot or cold) through the air-conditioning vents with the climate control switch in the off position and the blower fans blissfully silent. The modification is very simple to effect and easily reversible if you do not like it; but you will.

Remove the two screws holding the left side heater louver (at your right knee LHD cars) and then remove the panel by sliding it forward and down, towards the front of the car. Before you is the daunting intricacy of the climate control unit which strikes trepidation into even the most technically competent on this list (be brave, this is easy). Just below the vent aperture is a black box with a tangle of wires from several electrical connections and, just in front of that (towards the engine and to the right of a plastic drain tube) a silver box, about one inch square, with two electrical connections protruding downwards from a black plastic appendage. On my car, the appendage is embossed with the name AISIN. The connection closest to hand has two black wires (the one at the rear two pink). Disconnect the (black wire) connector by pulling straight down. This disables the vacuum solenoid that closes off the air intake (RTC 670 "vacuum valve", if you have a parts book).

You can now go for a drive and see if you like it. If you do, you will probably want to be able to turn it off at some time, in which case, obtain standard male and female, blade type, electrical connectors and mount them at each end of a piece of wire. Install a simple on / off switch in the wire and connect it between the contacts you have separated.

Your car will now give fresh air at outside ambient temperature (this not a substitute for air conditioning), or heated air, under the following conditions: Set the temperature control to maximum cooling, turn on the climate control and wait until the servo stops whirring indicating the air blend flaps have adjusted. Now turn off the climate control and a gentle breeze will be found blowing through the vents which is proportional to the forward velocity of the car. Opening the roof or a window increases flow. The temp control can also be reset to bring in heated air by switching on the climate control, selecting a higher temperature, and again waiting for the mechanism to adjust before turning it back off. If you have mounted the switch, the ventilation can now be turned on or off without the climate control in operation.

An interesting side effect is that removing the connection not only disables the vacuum solenoid but also one of the climate control blower fans. If you run the climate control as normal, with the ventilation switch on, there is only the noise from one fan and, of course, proportionally less air velocity. Therefore fitting the switch gives you the option of running one or two fans when using the climate control.

I have been using this modification for over a year now without a problem. (Other than the anxiety from hearing subtle engine noises which were not previously discernible with the climate control in operation).


Gregory Andrachuk

DONE! Some may remember that I complained that my late 82 had the early style vacuum valve, not the AISIN valve, and the vent modification to admit fresh air with the climate control OFF did not work. I procured a used AISIN valve (two, actually) and tried again, using the window master switch as the open/close switch for the fresh air flap. It works PERFECTLY. A gentle waft of fresh air. It worked WITHOUT first turning on the climate control, and although I have not yet tested it extensively, it seems to provide heated air using only the temperature selector, although in observing this, I must say that I had turned the climate control on briefly. Was I just getting the benefit of residual heat in the heater core? In any case, using the master switch, there seemed to be no difference in the sound of the fans. (I believe that Tony Gardner said that one fan would be cut out when the switch was set to open the fresh air flap.) Anyway, it works, and works very well and thanks to Tony Gardner and the other pioneers of this worthwhile modification. The best part, the only thing that encouraged me to do this, is the fact that it is completely reversible with absolutely no permanent change to the system, and no visible alteration. Both important if your car is more than a "driver".


Greg Price

I just finished performing Tony Gardner's fresh air mod on my '85 SIII XJ6. Everything works as specified. I routed two wires from the "AISIN" solenoid to the master electrical switch (the top center button on the console). Now the master electrical switch operates my fresh air vent, instead of locking the window buttons. If you do this, you will need to jumper the two wires you take off of the master electrical switch, or your windows won't operate. Thanks a bunch, Tony!!!!


Shane Mantoszko Describes Something Similar for the Series II

With all this discussion on modifying the series 3 climate control, I though I'd tell the list what modifications I did to my series 2, which is a slightly different system, but very similar, if not identical in it's functions.

Firstly, with regards to fresh air coming into the cabin. The series 2 has small mesh inlets above each headlight, with piping running to the footwell of the cabin. In each footwell is a knob which you can pull to open up this inlet, and allow fresh air into the footwells. It comes in right next to where the blower motors inlet is. Fresh air can also come in via the plenum box, through the grate in front of the windscreen (where the wiper-washer nozzle sits).

The system will open up the the flaps which sit on top of the fan blower units, and let fresh air in through the plenum box when using either full heat or full cold operation. All other times, the flaps should be closed, whether the climate control is on or off, thus giving recirculation.

This flap system after some years can be troublesome, so when my guy was re-building my climate control, and re-wiring the whole underdash with all new wiring,connectors and relays etc, I said to him ' since we have the fresh air option already via the top of the headlights, why the hell do I need to get air in through the plenum box ? Lets disconnect that whole part of the climate control, and seal up the flaps on top of the blower motors, so that the climate control works fully with re-circulation, and when I want fresh air to come in, I'll just pull the vent knobs in the footwell, or open one of the windows if I want high volume fresh air....' made sense to me, and after 6 months of driving with it, I can say that it is just sensational. I am a city boy, and just hated the volume of exhaust fumes which would come in through the climate c ontrol.....now I get much less, and just have to push a knob in the footwell to close it off completely. Also, now that the flaps from the plenum box are totally sealed, I don't have to worry about water gushing into the footwell when the drain tubes into the engine bay are blocked up...It will stay in the plenum box until It dribbles through the drains itself, or until I hear the water slushing around and clear the drain tubes out....


John Napoli Adds Manual Compressor Control to the SIII

Many of us have Gardnerized our cars, and this has proven to be a handy feature. In previous posts, I mentioned that I was going to experiment with compressor cutoffs, the idea being that you could run the climate control system withoout the compressor running. I performed this mod on my 84 S3 XJ6, and have found it to provide greater system flexibility and as much as 3 more miles per gallon. I did it by adding a switch in series to the compressor circuit. The approach I took was almost identical to that used to do the Gardner mod:

Remove the right hand console panel (the one under the instrument panel). Remove the right side underscuttle panel. Locate the inline fuse for the compressor -- it is a standard white inline fuse holder attached to the climate control system housing with a clamp. (It is located up and to the right of the air flap rods.)

Remove the clamp and remove the fuse. Start the car and turn on your climate control. If you have the right fuse, the compressor won't be runnng. Replace the fuse and the compressor starts. Switch off the engine -- now you know you're in the right place.

The long side of the fuse holder has a yellow wire with a black tracer coming out of it that leads to a white female spade connector. Remove that connector from the device its attached to. Notice that the connector has two yellow/black wires attached to it. We only care about the wire that leads to the fuse holder.

Cut the yellow/black wire that runs between the fuse holder and the connector right in the middle. Crimp on a female spade lug to one of the ends, and a male spade lug to the other. (This makes it easy to add the switch and also makes this mod reversible if you decide to deinstall later - -- just plug these two together.) If you are doing this with the fuse removed from the fuseholder, which gives you more slack to work with while you are doing this, be careful about the spring in the fuse holder that will want to pull the little stub end of wire out of your hands before you afix the connector.

Now, prepare another wire just like the one that you prepared for your Gardner mod, namely, a suitable length of zip cord. One end gets another male-female pair of spade connectors, and the other end gets whatever you need to attach it to your switch (a pair of females in my case). Plug the male-female end of the wire to the female-male connectors you added to the yellow/black wire.

I added a small 4 rocker switch panel from Pep Boys (8 bucks or thereabouts) inside my center console, since I didn't want to lose the functionality of the window lock switch, and I wanted more switches, anyway. Fish the wire through with a wire coat hangar. Plug in your switch and try it out. Replace the two panels you removed.

Results: this mod adds nice flexibility. Many days or evenings where it is warm enough for forced air circulation, but cool enough not to need the A/C, has made me appreciate the option of turning off the compressor and saving gasoline.. (Watch your computer with the compressor on and off -- you'll see a significant saving. I have averaged up to 3 mpg more over a tankful of gas.) And, of course, come winter the compressor can remain idle (except for a spin every couple of weeks to keep the seals moist).

I tend to keep the Gardner switch on all the time so the car always gets air from the outside, and use the compressor cutout switch as needed whenever I switch the climate control system on.

My next thought is to add a timer delay to the mix to cycle the compressor on and off while driving. More on this at a future date......

I would definitely recommend this modification to all.


Kyle Chatman Recommends an Alternative Switching Arrangement

I would like to share my method of adding switches with which I am pleased. I bought mini toggle switches and mounted them on a plexiglass "table" that fits inside the ash tray. (By table, I mean a flat top plate and two supporting plates, one near each end with holes drilled through for the wires.) With the plexiglass mounted flush against the underside of the chrome cigarette supporting piece (piece with funny dish- shaped support), the ashtray cover can be opened and closed, without interference, as you prefer. I usually leave it open because it looks James Bondish and my life can use a little safe and harmless excitement. My mounting has two switches because I added the modifications one at a time. Also, except for drilling holes in the ash can piece for wires to come through, there is no permanent change. Should not be a problem as even smokers leave their Jaguars to light-up, right? 8). The only "problem" I have is that I can't tighten the brace that holds the ashtray firmly in place. The location is perfect for shutting-off the compressor when the AC is on to leave traffic lights more quickly, to attack that hill more forcefully, or to pass that car more safely. I also suspect that a car thief would at least think twice about taking the car or radio. Let me know if you want to try it but don't understand my description.

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