Experience
in a Book
Air
Conditioner/Heater Mods
Modifying the climate control system? Actually, this
section describes a couple of the most popular modifications
to the XJ-S. Referred to as the Gardner/Napoli mods after
the guys who described them in detail on the Internet
discussion list, they provide an increased level of control
in a system that seems designed for as little control as
possible. It should be noted that these mods are described
as they apply to the early system, and may not apply to the
Delanair MkIII system. They also may not be needed in later
cars, since the later systems provide more control to begin
with.
NAPOLI MOD: The idea of this mod is simple enough:
provide a switch to enable operating the climate control
system without the compressor when cooling is not needed.
John Napoli says, "You are basically adding a switch in
series to the inline fuse for the compressor located on the
transmission tunnel near the air flap linkages." The wire in
question is a GN wire.
Note that operating with the compressor off will not only
result in no cooling, but will eliminate the ability to
dehumidify as well. In high humidity situations, you will
probably need to turn the compressor back on to prevent
window fogging and other humidity problems. You will
definitely need it on if you use "defrost" mode to clear
condensation on the windshield.
Also note that operation of the system in hot weather
with the compressor off might cause the "Auto" mode to
increase fan speeds, since it's trying to cool and the servo
is moving to ever more powerful cooling modes to try to
lower the temperature. However, normally the occupants will
want to switch the compressor on long before this happens.
Even if it did happen, it's simple enough to switch to "Low"
fan speed.
There is a fuel cooler in the freon circuit, and shutting
off the compressor will obviously result in a loss of fuel
cooling. According to Roger Bywater, "the fuel cooler was
added as an emission device, not because of fuel handling
difficulties like vapour lock, although this could happen on
early cars before the fuel rail temperature sensor was
introduced. The high underbonnet temperatures of the V12
always resulted in a lot of heat being transferred to the
tank with the recirculating fuel and I recall measuring over
60 degrees C at the tank which means a lot of vapour can be
given off. To pass a full EPA emission test for
certification there are strict limits on the evaporative
emissions of the whole vehicle (including adhesives, plastic
mouldings, paint, etc.) and the fuel cooler eased this
situation by reducing fuel vapour loss. This is why all cars
for the USA market had air conditioning - they were not
certified for sale without it. Also the convertible would
have to have the compressor running continually because the
air con would probably not be used with the top down."
Hence, the Napoli mod might technically be considered
detrimental to the emissions control systems of the car.
Note, however, that you would normally only switch the
compressor off on days where the weather was cool anyway;
presumably, the fuel needs cooling the most on the same days
that you do, when you will have the compressor on.
The guys who have computers in their cars report that
shutting off the compressor results in an instant fuel
economy increase along the order of 2 mpg. As always, your
mileage may vary, and in this case some of that benefit may
deteriorate as the fuel in the tank gets warmer; warm fuel
hurts engine efficiency. And if you roll the windows down,
all bets are off; open windows are detrimental to
aerodynamics, and if you're travelling at highway speeds the
benefits of turning the compressor off and opening the
windows may be a wash.
One final note: The stock system will already shut off
the compressor under either of two conditions: 1) the air
coming through the evaporator coil is too cold, or 2) the
system is calling for max heat. Hence, the Napoli mod should
not actually increase the heating capacity of the system;
when max heat is needed, the compressor is off anyway. If
this mod does noticeably improve heating performance, there
is something wrong in the control system; I'd recommend
adjusting the flaps per the procedure in Air
Conditioner/Heater.
GARDNER MOD: The system is clearly designed with
the intention that you will always have the climate
control system on when driving; when the system control knob
is turned to the "OFF" position, the fresh air/recirculation
flaps are moved to recirc position, positively closing off
the intake of fresh air. Tony Gardner's mod lets you drive
along with the climate control system switched off and still
have nice fresh air wafting through the dash vents. The
Gardner switch removes the ground from the vacuum solenoid
controlling the fresh air flaps, allowing the flaps to open
and fresh air to enter the cabin.
The vacuum solenoid in question is readily accessable;
simply remove the grille and pad on the left side of the
console (driver's side footwell on LHD cars), and the vacuum
solenoid is mounted just forward of the four-relay box.
Simply disconnect the ground wire, and connect it through a
switch.
The Gardner switch will hold the fresh air vents open
regardless of whether the system is on or off, but when the
system is on there isn't much point. During normal
operation, the system almost always keeps the fresh air
intakes open; the only time they are closed are during max
cool and max heat, which are relatively rare. However, as
noted above, the Napoli mod may cause the control to run to
max cool far more often, so the Gardner mod may come in
handy to use in concert with it.
For winter use, Gardner himself provides the following
tip: "If the climate control is set to heat (to adjust the
flaps) and then switched off, warm air flows through the
fresh air ducts. The vent mod does not replace AC, therefore
it actually works better in winter than summer."
GARDNER/NAPOLI MOD COMBINATION: Tom Bernett was
concerned about locating a profusion of switches in his XJ6.
"If you combine both of these mods on the same switch
(double pole, the circuits must be kept separate!) you can
eliminate one of the switches and simplify operation. In one
position the switch would make both the Gardner and Napoli
circuits (just as in the factory configuration), in the
other position the switch would break both circuits
(invoking both the Gardner and Napoli mods). Here is the way
this works under the 3 main operating modes of the A/C
system:
A/C System Off - The normal factory system
configuration includes vacuum solenoid energized (fresh
air flaps closed), and no power to compressor of course
(except late XJ-S convertibles). If you open the
combination switch (Gardner and Napoli circuits), vacuum
solenoid loses its ground (fresh air flaps open). Napoli
circuit has no effect since there is no power to
compressor anyway. If you close the combination switch,
the vacuum solenoid closes fresh air flaps (just like
factory configuration), and makes the Napoli circuit
(which has no effect since the A/C system is off and no
power is available to the compresssor).
A/C System On - Normal system configuration (except at
full cooling) includes vacuum solenoid de-energized
(fresh air flaps open), and power available to
compressor. Opening the combination switch cuts power to
the compressor (just like the solo Napoli switch), and
has no effect on the vacuum solenoid which is
de-energized anyway (except at full cooling, see below).
Closing the combination switch allows power to the
compressor, and makes the circuit for the vacuum solenoid
(which is de-energized anyway so there is no effect).
A/C System in Full Cooling - At full cooling the
combination switch will be closed of course, so you'd
have power to the compressor and the vacuum solenoid
energized to close the fresh air flaps for recirc and
max. cooling.
"As I said earlier, I'd rather not add another switch
which isn't necessary and which requires additional thought
and manual intervention (lessee... if I have the Gardner
switch closed, should I open the Napoli switch, etc.? ) It
seems easier to say "I want fresh air only, open the
combination switch with the A/C system off" or "I want
everything but compressor, open the switch with A/C system
on." or "I want normal operation, close the switch.""
GARDNER/NAPOLI MOD COMBINATION SWITCH: John Smith
sends this suggestion: "The interior drivers lamp switch,
the push on/push off switch next to the interior light
switch is - you guessed it - a double pole switch. I have
seldom used this switch for its intended purpose as it only
provides minimal lighting.
"I removed the switch, and to give it a `genuine` A/c
switch appearance I installed the letters`A/c` behind the
switch window.
"To do this the switch must be carefully dismantled by
drilling out the flaring of the small rivet and removing the
rivet. This will allow the small side cover to be removed.
Do this carefully because there are three springs and
two copper contacts which will be loose inside and you need
to note their position for reassembly.
"This will give access to the switch inner and allow you
to gently prise off the front cover revealing the silhouette
indicator piece of plastic with the lamp emblem. You will
also see three small rectangular opaque plastic light
diffusers. If you want a better looking and better lit
switch - do not re install these. I also recoated the inside
of the poorly painted white areas with liquid paper.
"On my bubblejet printer, I printed `A/c` using an 18pt
Ariel bold font with white print and black background.
"I carefully scraped away the lamp emblem, leaving a
small cleared rectangle to allow enough backlight through
for the `A/c` label which I glued to the front over the
scraped and cleared space. I sprayed the front with artist's
clear fixing spray and reinstalled within the front switch
cover and then reassembled the switch. Make sure you don`t
put the `A/c` label upside down. The little red window is at
the bottom and the green at the top.
"When refitting the switch side panel, make sure the hook
on the piece of spring wire attached to this panel, engages
in the in/out white plastic mechanism. A very small self
tapping screw will replace the rivet.
"Wiring is as follows. Cut the connector wires about one
inch back from the connector. Put the connector to one side.
Get hold of the cut loom wires and join the the purple and
the purple/ blue wires together. Tape off the ends of the
black wire and the purple/white wire. These are not positive
leads but it is best to tape them out of harm's way.
"Now the connector. Prise the connector cover open and
relocate the brass terminal loop attached to the purple/blue
wire from position 7 to position 9 alongside the purple
wire. To check the wiring is correct, attach the connector
to the switch and make sure there is continuity between the
purple and purple/blue, and continuity between the black and
purple/white when the switch is pushed in to the on
position.
"To complete the wiring, hook up the vacuum (fresh air)
wiring to the purple and purple/ blue wires and similarly,
the A/c clutch wires to the black and purple/white wires. I
soldered the joints and insulated them with heat shrink
tubing to make a secure neat job.
"Reinstall the switch and it looks and works in a totally
professional way."
NAPOLI'S MOD TO THE GARDNER MOD (!): "Instead of
wiring the Gardner switch to cut out the ground, wire it to
apply power to the solenoid. Then, whenever you want recirc,
regardless of the mode the climate control system is in, you
can get it. You also preserve full Gardner functionality
with the climate control off -- just switch off the switch."
Essentially, the regular Gardner mod switch is OPEN/AUTO,
while in this scheme it is OPEN/CLOSED -- complete manual
control of the recirc flap.
POLLEN FILTERS: Richard Mansell reports: "If you
are interested you can get pollen filters for the
ventilation system. I have no idea how or where you fit them
but according to a Jaguar accessories brochure from 1997
three are available:
93.5-96 JLM11696
92-93 JLM11355
Pre-92 JLM11108
On to
Stereo
Modifications
|