1995 TOYOTA SUPRA cooling

CAUTION:
wBe sure to connect both the high and low pressure
quick±connectors onto the A/C system when evacuating.
If only one side is connected, the system would be open
to atmosphere through the other connector, making it
impossible to maintain vacuum.
wBe sure to turn off the manifold gauge valve immediately
after evacuating the system. Then you may switch off the
vacuum pump.
PRECAUTIONS WHEN CHARGING
REFRIGERANT
1. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH
REFRIGERANT IN REFRIGERANT SYSTEM
If there is not enough refrigerant in the refrigerant system, oil
lubrication will be insufficient and compressor burnout may
occur, so take care to avoid this.
2. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILST COMPRESSOR IS OPERATING
If the high pressure valve is opened, refrigerant flows in the
reverse direction and could cause the charging cylinder to
rupture, so open and close the low pressure valve only.
3. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as in-
sufficient cooling, poor fuel economy, engine overheating
etc.
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
Failure to carry out service operations in the correct se-
quence could cause the supplemental restraint system to
deploy, possibly leading to a serious accident.
During removal or installation of the parts and the yellow wire
harness and connector for the airbag is necessary, refer to
the precautionary notices in the RS section before carrying
out operation. AC±6
± AIR CONDITIONING SYSTEMGENERAL DESCRIPTION

HINT:
wIf the instruction ºProceed to next circuit inspection shown on matrix chart is given in the flow chart
for each circuit, proceed to the circuit with the next highest number in the table to continue the check.
wIf the trouble still reappears even though there are no abnormalities in any of the other circuits, then
check or replace the A/C amplifier.
AC±52
AC±54
AC±56
AC±58
AC±60
AC±62
AC±66
AC±69
IN±35
AC±71
AC±76
AC±77
AC±107
AC±92
AC±91
AC±95
AC±96
AC±98
AC±97
IG power source circuitBackup power source
circuitACC power source circuitHeater relay circuitCompressor circuitBlower motor circuitA/C amplifierTemperature set dial circuitA/C control assembly circuitRefrigeration system inspection
with manifold gauge setElectric cooling fanWater valveDrive belt tensionRefrigerant volumeCondenserExpansion valveEvaporatorHeater radiatorReceiver
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±27

Blinking Light FOOT Evaporator Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the
A/C amplifier.
Diagnostic Sensor Check Detecting ConditionTrouble Area
Open or short in evaporator temperature sensor
circuit.
Evaporator temperature sensor

Harness or connector between evaporator
temperature sensor and A/C amplifier

A/C amplifier
AC±32± AIR CONDITIONING SYSTEMTROUBLESHOOTING

2. MOISTURE PRESENT IN REFRIGERATION SYSTEM
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

During operation, pres±
sure on low pressure
side sometimes
becomes a vacuum and
sometimes normal
Moisture entered in re±
frigeration system
freezes at expansion
valve orifice and tem±
porarily stops cycle, but
normal state is restored
after a time when the ice
melts(1) Replace receiver/drier
(2) Remove moisture in
cycle through repeat±
edly evacuating air
(3) Charge new refriger±
ant to proper amount
Drier in oversaturated
state

Moisture in refrigeration
system freezes at ex±
pansion valve orifice
and blocks circulation of
refrigerant
Condition: Periodically cools and then fails to cool
3. INSUFFICIENT REFRIGERANT
Symptom seen in
refrigeration system
Condition: insufficient cooling
Probable causeDiagnosisRemedy

Pressure low on both
low and high pressure
sides

Bubbles seen in sight
glass continuously

insufficient cooling
performance
Gas leakage at some
place in refrigeration
system
Insufficient refrigerant
in system

Refrigerant leaking(1) Check for gas leak
age with leak detec±
tor and repair if nec±
essary
(2) Charge refrigerant to
proper amount
(3) If pressure indicated
value is near 0 when
connected to gauge,
create the vacuum
after inspecting and
repairing the location
of the leak
AC±72± AIR CONDITIONING SYSTEMTROUBLESHOOTING

4. POOR CIRCULATION OF REFRIGERANT
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure low on both
low and high pressure
sides

Frost on tubes from
receiver to unit
Refrigerant flow
obstructed by dirt in
receiver
Receiver clogged
Replace receiver
Condition: insufficient cooling
5. REFRIGERANT DOES NOT CIRCULATE
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Vacuum indicated on
low pressure side, very
low pressure indicted
on high pressure side

Frost or dew seen on
piping before and after
receiver/drier or expan±
sion valve
Refrigerant flow
obstructed by moisture
or dirt in refrigeration
system

Refrigerant flow ob±
structed by gas leakage
from expansion valve
heat sensing tube
Refrigerant does not
circulate(1) Check heat sensing
tube, expansion valve
and ERP
(2) Clean out dirt inexpan±
sion valve by blowing
with air
If not able to remove
dirt, replace expansion
valve
(3) Replace receiver
(4) Evacuate air and
charge new refrigerant
to proper amount.
for gas leakage from
heat sensing tube, re
place expansion valve.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±73

6. REFRIGERANT OVERCHARGE OR INSUFFICIENT COOLING OF CONDENSER
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
(1) Clean condenser
(2) Check fan motor
operation
(3) If (1) and (2) are in
normal state, check
amount of refrigerant
Charge proper amount
of refrigerant
Pressure too high on both
low and high pressure
sides

No air bubbles seen
through the sight of glass
even when the engine
rpm is lowered.
Unable to develop
sufficient performance
due to excessive
refrigerant in system

Insufficient cooling of
condenser
Excessive refrigerant in
in cycle " refrigerant
overcharged

Condenser cooling
insufficient " condenser
fins clogged or fan motor
faulty
Condition: Insufficient Cooling
7. AIR PRESENT IN REFRIGERATION SYSTEM
Condition: insufficient cooling
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
(1) Check compressor oil to
see if dirty or insufficient
(2) Evacuate air and charge
new refrigerant
Pressure too high on both
low and high pressure
sides

The low pressure piping is
hot to the touch

Bubbles seen in sight
glass
Air entered in
refrigeration system
Air present in
refrigeration system
NOTE: These gauge indications are shown when the refrigeration
system has been opened and the refrigerant charged without
vacuum purging.

Insufficient vacuum
purging
AC±74± AIR CONDITIONING SYSTEMTROUBLESHOOTING

8. EXPANSION VALVE IMPROPERLY
MOUNTED/HEAT SENSING TUBE DEFECTIVE
(OPENS TOO WIDE)
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
(1) Check heat sensing tube
installed condition
(2) if (1) is normal, check
expansion valve
Replace if defective
Pressure too high on both
low and high pressure
sides

Frost or large amount of
dew on piping on low
pressure side
Trouble in expansion
valve or heat sensing tube
not installed correctly
Excessive refrigerant in
low pressure piping
Condition: Insufficient cooling

Expansion valve opened
too wide
9. DEFECTIVE COMPRESSION COMPRESSOR
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
Condition: Does not cool

Repair or replace
compressor
Pressure too high on
low pressure sides

Pressure too low on
high pressure side
Internal leak in
compressor
Compression defective

Valve leaking or broken,
sliding parts
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±75

REFRIGERANT VOLUME
REFRIGERANT VOLUME INSPECTION
1. RUN ENGINE AT APPROX. 1,500 RPM
2. SET TEMPERATURE CONTROL AT MAX. COOL
3. SET BLOWER SWITCH AT ºHIº
4. SET AIR INLET CONTROL AT ºRECIRCº
5. TURN A/C SWITCH ON
6. FULLY OPEN DOORS
7. INSPECT AMOUNT OF REFRIGERANT
Observe the sight glass on the liquid tube.
 Item Symptom Amount of refrigerant Remedy
 
 
 
 
1
 
 
 
 
Bubbles present in sight glass
 
 
 
 
Insufficient*
 
 
 
 
(1) Check for gas leakage with gas leak
tester and repair if necessary
(2) Add refrigerant until bubbles dis±
appear
 
 2
 
 No bubbles present in sight glass
 
 
None, sufficient or too
much 
 Refer to items 3 and 4
 
 
 
 
3
 
 
 
 
No temperature difference between
compressor inlet and outlet
 
 
 
 
Empty or nearly empty
 
 
 
 
(1) Check for gas leakage with gas leak
tester and repair if necessary
(2) Add refrigerant until bubbles disap-
pear
 
 4 
 
Temperature between compressor
inlet and outlet is noticeably different 
 Correct or too much 
 Refer to items 5 and 6
 
 
 
5
 
 
 
Immediately after air conditioning is
turned off, refrigerant in sight glass
stays clear 
 
 
Too much
 
 
 
(1) Discharge refrigerant
(2) Evacuate air and charge proper
amount of purified refrigerant
 
 
 
6
 
 
 
When air conditioning is turned off,
refrigerant foams and then stays
clear 
 
 
Correct
 
 
 
±±
* Bubbles in the sight glass with ambient temperatures higher
than usual can be considered normal if cooling is sufficient.
REFRIGERANT CHARGE VOLUME
Specified amount:
700 + 50 g (24.96 + 1.76 oz.)
AC±76± AIR CONDITIONING SYSTEMREFRIGERANT VOLUME