heating LEXUS SC400 1991 Service User Guide

DATE:NOVEMBER 29, 1996
TitleALTERNATE REFRIGERANTS AND A/C RETROFITPage 1 of 2
Effective January 1, 1996, the E.P.A. has officially banned the manufacture of Refrigerant 12 (Freon).
As a result, surplus supplies of R±12 will begin to dwindle over the ne\
xt several years until, eventually,
R±12 will no longer be available.
This uncertainty about the availability of R±12 has caused significant concerns for Lexus dealers when
servicing HVAC systems not using R±134a refrigerant. Similarly, the reduced availability of R±12 has
prompted demands for R±134a retrofit kits and/or alternate refrigerants. Thi\
s TSB will clarify Lexus's
current recommendations for servicing and retrofitting HVAC systems on Lexus vehicles using R±12
refrigerant.
ALTERNATE REFRIGERANTS:
Previously, the E.P.A. has endorsed other alternative refrigerants. These endorsements, combin\
ed with
the uncertain future availability of R±12, have lead to a limited accept\
ance of using alternative refrigerants
when servicing or retrofitting R±12 HVAC systems. Use of these refrigerants can lead to several service
related problems, including:
Poor system performance and leak detection capabilities.
Contamination of R±12 and R±134a during refrigerant recovery and r\
ecycling.
Recently the E.P.A. released a statement clarifying that approval of alternative refrige\
rants relates only
to the toxicology, flammability, ozone depletion and global warming characteristics. The approval does
not imply acceptability of alternative refrigerants use with respect to serviceability or performance.
TOYOTA MOTOR SALES, U.S.A. ENDORSES THE USE OF R±134a AS THE ONLY ACCEPTABLE ALTERNATIVE REFRIGERANT FOR VEHICLES USING R±12.
R±12 AVAILABILITY:
It is estimated that existing R±12 supplies will meet market demand i\
n 1996. Beyond that, Lexus will
supply R±12 to it's dealers from a strategic reserve. These strategic reserves are alloca\
ted specifically
for distribution to Lexus dealers for repair of their customers' R±12 H\
VAC systems. TMS projects these
reserves may meet dealer demand through early 1998. After that, we believe R±12 will no longer be re\
adi-
ly available and dealers will begin to retrofit customer vehicles with R\
±134a.
REF: HEATING & AIR CONDITIONING
NO:AC007±96
MODEL:ALL MODELS
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ALTERNATIVE REFRIGERANTSPage 1 of 1
Beginning with the Montreal Protocol signed in April 1988, auto manufacturers wor\
ld±wide
committed to phase±out the use of ozone damaging Refrigerant R±12,\
also known as Freon.
All automobile manufacturers are re±designing new production vehicles\
to use non-ozone depleting
R±134a which is the only
universally approved replacement refrigerant for R±12.
All 1994 and newer Lexus use R±134a.
Several independent companies have begun marketing alternative refrigerants whi\
ch they claim can
replace R±12 when servicing vehicles in the dealership. These R±12 repla\
cements commonly
referred to as blends or hydrocarbon based refrigerants, have the potent\
ial to cause damage to
Lexus AC systems and in some cases can cause personal injury to the serv\
ice technician or the
end±user. Lexus strongly discourages the use of these refrigerants in Lexus vehicl\
es.
Furthermore, dealer technicians should be cautious of vehicles that may be labeled o\
r otherwise
identified to contain such refrigerants. Servicing these vehicles can contaminate your AC
refrigerant recovery equipment causing refrigerant stored in the recovery machine to be rendered
unusable. Also, if the contaminated refrigerant equipment is then used on subseq\
uent repairs, the
dealer may unknowingly contaminate other owner's vehicles.
For all Lexus models and years that are designed to operate on R±12, \
continue to service with
R±12 as long as it is available which is expected to be two or more years. When research is
complete and R±12 becomes difficult to acquire, Lexus will provide parts and procedures to properly
retrofit an R±12 vehicle to non±ozone depleting R±134a.
HEATING & AIR
CONDITIONING
AC94±001
MARCH 25, 1994
ALL MODELS
WhereEverybodyKnowsYourName

DATE:NOVEMBER 29, 1996
TitleALTERNATE REFRIGERANTS AND A/C RETROFITPage 1 of 2
Effective January 1, 1996, the E.P.A. has officially banned the manufacture of Refrigerant 12 (Freon).
As a result, surplus supplies of R±12 will begin to dwindle over the ne\
xt several years until, eventually,
R±12 will no longer be available.
This uncertainty about the availability of R±12 has caused significant concerns for Lexus dealers when
servicing HVAC systems not using R±134a refrigerant. Similarly, the reduced availability of R±12 has
prompted demands for R±134a retrofit kits and/or alternate refrigerants. Thi\
s TSB will clarify Lexus's
current recommendations for servicing and retrofitting HVAC systems on Lexus vehicles using R±12
refrigerant.
ALTERNATE REFRIGERANTS:
Previously, the E.P.A. has endorsed other alternative refrigerants. These endorsements, combin\
ed with
the uncertain future availability of R±12, have lead to a limited accept\
ance of using alternative refrigerants
when servicing or retrofitting R±12 HVAC systems. Use of these refrigerants can lead to several service
related problems, including:
Poor system performance and leak detection capabilities.
Contamination of R±12 and R±134a during refrigerant recovery and r\
ecycling.
Recently the E.P.A. released a statement clarifying that approval of alternative refrige\
rants relates only
to the toxicology, flammability, ozone depletion and global warming characteristics. The approval does
not imply acceptability of alternative refrigerants use with respect to serviceability or performance.
TOYOTA MOTOR SALES, U.S.A. ENDORSES THE USE OF R±134a AS THE ONLY ACCEPTABLE ALTERNATIVE REFRIGERANT FOR VEHICLES USING R±12.
R±12 AVAILABILITY:
It is estimated that existing R±12 supplies will meet market demand i\
n 1996. Beyond that, Lexus will
supply R±12 to it's dealers from a strategic reserve. These strategic reserves are alloca\
ted specifically
for distribution to Lexus dealers for repair of their customers' R±12 H\
VAC systems. TMS projects these
reserves may meet dealer demand through early 1998. After that, we believe R±12 will no longer be re\
adi-
ly available and dealers will begin to retrofit customer vehicles with R\
±134a.
REF: HEATING & AIR CONDITIONING
NO:AC007±96
MODEL:ALL MODELS
WhereEverybodyKnowsYourName

SERVICE HINTS FOR REFRIGERANT LEAK DETECTIONPage 1 of 3
Use of electronic leak detectors for checking A/C systems refrigerant leaka\
ge is the only
method approved by TMS. This type of leak detector is sensitive not onl\
y to refrigerant, but
also sensitive to numerous petrochemical substances (motor oil, gasolin\
e, solvents, etc.)
commonly found in a repair shop environment. Because this sensitivity c\
ould diminish the leak
detector 's capacity for accurate leak detection, some service hints have been pro\
vided to help
increase the accuracy of your diagnosis.
SERVICE HINTS:
1. Visual Inspection: Do a quick visual inspection under the hood for signs of refrigerant
leakage. Check for areas of heavy oil leakage at block and piping joint\
s. Many times
these areas have accumulated road dust and dirt.
2. Inspection with leak detector: NOTE: Make sure the system is fully charged. Operate
the system to increase refrigerant pressure. Shut the system off before inspecting with
leak detector.
A. Checking for leakage at a joint:
Wipe the oil/dirt accumulation off the joint with a
clean rag. Do not use solvents to clean the joint. Refrigerant is heavi\
er than air so
start checking for leaks with the detector wand about 1/4 in. below the \
joint. Move the
wand slowly across and around each joint (see illustration below).
Piping Joint Move detector wand slowly across
and around each joint.
Block Joint
HEATING &
AIR CONDITIONING
AC95±001
MARCH 03, 1995
ALL MODELS
WhereEverybodyKnowsYourName

METER, ANALOGCurrent flow activates a magnetic
coil which causes a needle to
move, thereby providing a relative
display against a background
calibration.
LED (LIGHT EMITTING DIODE)
Upon current flow, these diodes
emit light without producing the
heat of a comparable light.
IGNITION COIL
Converts low±voltage DC current
into high±voltage ignition current
for firing the spark plugs.
1. SINGLE
FILAMENT
GROUND
The point at which wiring attaches
to the Body, thereby providing a
return path for an electrical circuit;
without a ground, current cannot
flow. Current flow causes a headlight
filament to heat up and emit light.
A headlight may have either a
single (1) filament or a double (2)
filament.
BATTERY
Stores chemical energy and
converts it into electrical energy.
Provides DC current for the auto's
various electrical circuits.
CAPACITOR (Condenser) A small holding unit for temporary
storage of electrical voltage.
CIRCUIT BREAKER Basically a reusable fuse, a circuit
breaker will heat and open if too
much current flows through it. Some
units automatically reset when cool,
others must be manually reset.
DIODE A semiconductor which allows
current flow in only one direction.
DIODE, ZENER A diode which allows current flow
in one direction but blocks reverse
flow only up to a specific voltage.
Above that potential, it passes the
excess voltage. This acts as a
simple voltage regulator.
FUSE A thin metal strip which burns
through when too much current
flows through it, thereby stopping
current flow and protecting a
circuit from damage.
FUSIBLE LINK A heavy±gauge wire placed in
high amperage circuits which
burns through on overloads,
thereby protecting the circuit.
The numbers indicate the cross±
section surface area of the wires. HORN
An electric device which sounds a
loud audible signal.
LIGHT Current flow through a filament
causes the filament to heat up
and emit light.
METER, DIGITAL Current flow activates one or
many LED's, LCD's, or fluorescent
displays, which provide a relative
or digital display.
MOTOR A power unit which converts
electrical energy into mechanical
energy, especially rotary motion.
CIGARETTE LIGHTER
An electric resistance heating
element.
DISTRIBUTOR, IIA Channels high±voltage current
from the ignition coil to the
individual spark plugs. 2. DOUBLE
FILAMENT
HEADLIGHTS
FUEL
(for High Current Fuse or
Fusible Link)
(for Medium Current Fuse)
M
16
GLOSSARY OF TERMS AND SYMBOLS
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