Lexus ES300 (1997 year). Manual — part 30

N20242

Sight Glass

AC2SY–01

I01386

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

AC–3

1560

1997 LEXUS ES300 (RM511U)

ON–VEHICLE INSPECTION

1.

INSPECT REFRIGERANT VOLUME

Observe the sight glass on the liquid tube.

Test conditions:

Running engine at 1,500 rpm

Blower speed control switch set at ”HI”

A/C switch ON

Temperature control set at ”MAX. COOL”

Fully open doors

Item

Symptom

Amount of refrigerant

Remedy

1

Bubbles present in sight glass

*Insufficient

(1) Check for gas leakage with gas leak de-

tector and repair if necessary

(2) Add refrigerant until bubbles disappear

2

No bubbles present i sight glass

None, sufficient or too much

Refer to item 3 and 4

3

No temperature difference between com-

pressor inlet and outlet

Empty or nearly empty

(1) Check for gas leakage with gas leak de-

tector and repair if necessary

(2) Add refrigerant until bubbles disappear

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 new refrigerant

6

When air conditioning is turned off, refriger-

ant foams and then stays clear

Correct

–

HINT:
*: Bubbles in the sight glass with ambient temperatures higher
than usual can be considered normal if cooling is sufficient.
2.

INSPECT REFRIGERANT PRESSURE WITH MAN-
IFOLD GAUGE SET

This is a method in witch the trouble is located by using a man-
ifold gauge set. Read the manifold gauge pressure when the
these conditions are established.

Test conditions:

Temperature at the air inlet with the switch set
at RECIRC is 30 – 35

°

C (86 – 95

°

F)

Engine running at 1,500 rpm

Blower speed control set at ”HI”

Temperature control set at ”MAX COOL”

(1)

Normally functioning refrigeration system

Gauge reading:
Low pressure side: 0.15 – 0.25 MPa (1.5 – 2.5 kgf/cm

2

)

High pressure side: 0.15 – 0.25 MPa (1.5 – 2.5 kgf/cm

2

)

I01387

Condition : Periodically cools and then fails to cool

I01388

Condition: Insufficient cooling

AC–4

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

1561

1997 LEXUS ES300 (RM511U)

(2)

Moisture present in refrigeration system.

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

During operation, pressure on low

pressure side sometimes become

a vacuum and sometime normal

Moisture entered in refrigeration

system freezes at expansion valve

orifice and temporarily stops cycle,

but normal state is restored after a

time when the ice melts

Drier in oversaturated state

Moisture in refrigeration system

freezes at expansion valve orifice

and blocks circulation of refriger-

ant

(1) Replace receiver

(2) Remove moisture in cycle

through repeatedly evacuating air

(3) Charge proper amount of new

refrigerant

(3)

Insufficient cooling

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Pressure low on both low and

high pressure sides

Bubbles seen in sight glass con-

tinuously

Insufficient cooling performance

Gas leakage at some place in re-

frigeration system

Insufficient refrigerant in sys-

tem

Refrigerant leaking

(1) Check for gas leakage with gas

leak detector and repair if neces-

sary

(2) Charge proper amount of re-

frigerant

(3) If indicated pressure value is

near 0 when connected to gauge,

create the vacuum after inspecting

and repairing the location of the

leak

I01389

Condition: Insufficient cooling

I01449

Condition: Does not cool (Cools from time to time in some cases)

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

AC–5

1562

1997 LEXUS ES300 (RM511U)

(4)

Poor circulation of refrigerant

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Pressure low in both low and

high pressure sides

Frost on tube from receiver to

unit

Refrigerant flow obstructed by dirt

in receiver

Receiver clogged

Replace receiver

(5)

Refrigerant does not circulate

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Vacuum indicated on low pres-

sure side, very low pressure indi-

cated on high pressure side

Frost or dew seen on piping be-

fore and after receiver/ drier or ex-

pansion valve

Refrigerant flow obstructed by

moisture or dirt in refrigeration sys-

tem

Refrigerant flow obstructed by

gas leakage from expansion valve

Refrigerant does not circulate

(1) Check expansion valve

(2) Clean out dirt in expansion

valve by blowing with air

(3) Replace receiver

(4) Evacuate air and charge new

refrigerant to proper amount

(5) For gas leakage from expan-

sion valve, replace expansion

valve

I01390

Condition: Insufficient cooling

I01392

Condition: Insufficient cooling

NOTE : These gauge indica-
tions are shown when the
refrigeration system has
been opened and the refrig-
erant charged without vacu-
um purging.

AC–6

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

1563

1997 LEXUS ES300 (RM511U)

(6)

Refrigerant overcharged or insufficient cooling of
condenser

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Pressure too high on both low

and high pressure sides

No air bubbles seen through the

sight glass even when the engine

rpm is lowered

Unable to develop sufficient per-

formance due to excessive refrig-

eration system

Insufficient cooling of condenser

Excessive refrigerant in

cycle

→

refrigerant over charged

Condenser cooling

→

condenser

fins clogged of condenser fan

faulty

(1) Clean condenser

(2) Check condenser fan motor

operation

(3) If (1) and (2) are in normal

state, check amount of refrigerant

Charge proper amount of refriger-

ant

(7)

Air present in refrigeration system

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Pressure too high on both low

and high pressure sides

The low pressure piping hot to

touch

Bubbles seen in sight glass

Air entered in refrigeration system

Air present in refrigeration sys-

tem

Insufficient vacuum purging

(1) Check compressor oil to see if

it is dirty or insufficient

(2) Evacuate air and charge new

refrigerant