Lexus GS300/400 (2000 year). Service manual — part 7

I01387

Condition : Periodically cools and then fails to cool

I01388

Condition: Insufficient cooling

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

AC–5

2690

(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

Dryer in oversaturated state

Moisture in refrigeration system

freezes at expansion valve orifice

and blocks circulation of refriger-

ant

(1) Replace dryer

(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 system

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)

AC–6

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

2691

(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 condenser to

unit

Refrigerant flow obstructed by dirt

in condenser

condenser clogged

Replace condenser

(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 condenser/ dryer or

expansion 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 condenser

(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.

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

AC–7

2692

(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

I01450

Condition: Insufficient cooling

I01393

Condition : Does not cool

AC–8

–

AIR CONDITIONING

AIR CONDITIONING SYSTEM

2693

(8)

Expansion valve improperly

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

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

Excessive refrigerant in low

pressure piping

Expansion valve opened too

wide

Check expansion valve

Replace if defective

(9)

Defective compression compressor

Symptom seen in

refrigeration system

Probable cause

Diagnosis

Remedy

Pressure too high on low and

high pressure sides

Pressure too low on high pres-

sure side

Internal leak in compressor

Compression defective

Valve leaking or broken sliding

parts

Repair or replace compressor