Aircondition, How it works??

Hi Daniel! Doug has given a great synopsis. On my XJS I've learned that the AC will NOT produce any cool air if the inside/ not outside air temps are above 60^F. So on a cold morning I get hot air from the left side drivers vent UNTIL the inside temp is about 70^-72^. Then you can begin to use the slide control-which actually does control the mixture and division of cooler air to the side vents. HOWEVER, in order to really experience this fine tuning of 'climate control' you really have to be in the car with interior conditions stabilized which in my car takes a good 45 minutes minimum. Until then only the left temp control makes a 'detectable'/ noticible difference. In really cold weather or really hot weather- the unit produces only Heat or Good AC-IF the AC system is charged and functioning properly. But on a long trip of several hours, that fine tuning slide really does work with the temp control set at a horizontal position
Sherman D. Taffel, Pres.
Columbia, MD
NCJOC
'72 E Type Ser III Coupe
'76 XJ12C
'89 XJS Convert
'96 XJR

If the windows don't clear after a few minutes of driving then I suspect you have water trapped in the ductwork or in the casing of the climate control, or water is entering thru the outside air intake. There are drains for the system under the car on each side of the transmission tunnel. They are often clogged. Also, the air inlet has two drains on the engine side of the bulkhead....you'll recognize them by the large rubber connectors and long pipes running along each inner fender.

Are you getting a sweet smell inside tha cabin as you drive? If "yes", then I would suspect a leaking heater core....

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

"When I drive with the car, the window on my side ist sometimes a little "fitted". How can I reduce this "problem"?"

I'm afraid I don't understand what you mean by "fitted"

As for the left control knob I generally leave it "in for auto". I leave the lower slide control in mid-position as it is only a fine tuning adjustment and doesn't have much influence.

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

fitted -> thats electonicaly translated (www.altavista.com) ;-)))

Now, I hope I find the right word:

When I drive with the car, the window on my side ist sometimes a little covered with damp / clouded / steamed. How can I reduce this "problem.

Doug, I hope you understand me now ;-)) Sorry about the language!

----------------------
see you on the road again

Daniel

"When I drive with the car, the window on my side ist sometimes a little "fitted". How can I reduce this "problem"?"

I'm afraid I don't understand what you mean by "fitted"

As for the left control knob I generally leave it "in for auto". I leave the lower slide control in mid-position as it is only a fine tuning adjustment and doesn't have much influence.

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Edited on 2004-12-12 14:24:44

Thanks for the cool replay.

Thats what I thought; it will never stop. Crazy.

@ Doug

"...lthough the system was designed for ease of use, I would certainly prefer more flexibilty in how it can be used. I'll admit, though, that 75% of the time I have the system set at 72? and "norm" and never even think about it....which, of course, was the true design intent of the system..."

Do you let the left switch for "auto" or "manual" and the Lower slide control in which position?

Now, we have here in switzerland terrible wheater, foggy (up to 2500 feet) and about 25F. When I drive with the car, the window on my side ist sometimes a little "fitted". How can I reduce this "problem"?

----------------------
see you on the road again

Daniel

"When is the AC starting to cool really?"

It never stops cooling. All air entering the car is cooled first, then heated when necessary.

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Jaguar, like many manufacturers, didn't consider it to be be air condtioning. It is a "climate control" system. Part of this is continual dehumidification of incoming air and thus designing the system so that the compressor is functional in all modes.

Although the system was designed for ease of use, I would certainly prefer more flexibilty in how it can be used. I'll admit, though, that 75% of the time I have the system set at 72? and "norm" and never even think about it....which, of course, was the true design intent of the system.

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

The problem with the vent system in the XJS is that whether you are heating or cooling, the AC runs. In order to get any ventilation, the AC system is engaged. Why? Who knows. That's the way it was designed. So no matter what temperature you set the control to... heating or cooling... the AC compressor is running. Basically, you can't turn the AC off, other than turning the whole system off.

Steve Weinstein, JTC-NJ
'70 XKE FHC
'69 XKE OTS
Former '89 XJS owner

Thank you Doug for the explanation. So far, so good. But:

When is the AC starting to cool really? In the modern cars, you have a switch ON/OFF for the AC, but here....???

All the other functions I "try" to understand ;-))

----------------------
see you on the road again

Daniel

Thank Doug for the explanation. So far, so good. But:

When is the AC starting to cool really? In the modern cars, you have a switch ON/OFF for the AC, but here....???

All the other functions I "try" to understand ;-))

----------------------
see you on the road again

Daniel

When everything is working properly, which isn't always the case, it works like this.....

Right side control knob:
"Off" is off. Any of the other settings are "on".
"Norm" will automatically adjust fan speeds and hot/cold blending to maintain the cabin temperature at selected with the left control knob.
"Low" performs the same function but eliminates auto-adjustment of fan speed, giving low speed only. Similary, "high" gives only the highest fan speed. The defrost position (12:00 o'clock on the dial) gives max heat and fan speed to clear the windshield.

Left side control knob:
This is where you adjust your desired cabin temperature. Pulling the knob outward gives manual temperature control, defeating the auto-regulation function of the system

Lower slide control:
This is a "trim" adjustment to alter the temperature of output from the upper outlets versus the footwell outlets.

If the system is trying to cool the car then almost all of the output comes from the large center dashboard outlet, with a small amount from the footwells. If heat is called for, most of the output goes to the footwells with a smaller output from the left and right dashboard outlets.

In a nutshell....that's it

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe