Infiniti M35/M45 Y50. Manual — part 138

TROUBLE DIAGNOSIS

ATC-103

C

D

E

F

G

H

I

K

L

M

A

B

ATC

Test Reading (VK45DE)

Recirculating-to-discharge Air Temperature Table

Ambient Air Temperature-to-operating Pressure Table

Inside air (Recirculating air) at blower assembly inlet

Discharge air temperature at center ventilator

°

C (

°

F)

Relative humidity

%

Air temperature

°

C (

°

F)

50 - 60

20 (68)

6.0 - 7.4 (43 - 45)

25 (77)

8.9 - 10.6 (48 - 51)

30 (86)

12.5 - 14.6 (55 - 58)

35 (95)

16.7 - 19.4 (62 - 67)

60 - 70

20 (68)

7.4 - 8.7 (45 - 48)

25 (77)

10.6 - 12.2 (51 - 54)

30 (86)

14.6 - 16.7 (58 - 62)

35 (95)

19.4 - 22.1 (67 - 72)

Ambient air

High-pressure (Discharge side)

kPa (kg/cm

2

, psi)

Low-pressure (Suction side)

kPa (kg/cm

2

, psi)

Relative humidity

%

Air temperature

°

C (

°

F)

50 - 70

20 (68)

907 - 1,106

(9.3 - 11.3, 131.5 - 160.4)

192 - 238

(2.0 - 2.4, 27.8 - 34.5)

25 (77)

987 - 1,207

(10.1 - 12.3, 143.1 - 175.0)

210 - 262

(2.1 - 2.7, 30.5 - 38.0)

30 (86)

1,072 - 1,312

(10.9 - 13.4, 155.4 - 190.2)

233 - 284

(2.4 - 2.9, 33.8 - 41.2)

35 (95)

1,168 - 1,425

(11.9 - 14.5, 169.4 - 206.6)

258 - 320

(2.6 - 3.3, 37.4 - 46.4)

40 (104)

1,272 - 1,550

(13.0 - 15.8, 184.4 - 224.8)

288 - 356

(2.9 - 3.6, 41.8 - 51.6)

ATC-104

TROUBLE DIAGNOSIS

TROUBLE DIAGNOSIS FOR UNUSUAL PRESSURE

Whenever system’s high and/or low side pressure(s) is/are unusual, diagnose using a manifold gauge. The
marker above the gauge scale in the following tables indicates the standard (usual) pressure range. Since the
standard (usual) pressure, however, differs from vehicle to vehicle, refer to above table (Ambient air tempera-
ture-to-operating pressure table).

Both High- and Low-pressure Sides are Too High

High-pressure Side is Too High and Low-pressure Side is Too Low

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Both high- and low-pressure sides
are too high.

The pressure returns to nor-
mal soon after water is
splashed on condenser.

Excessive refrigerant charge
in refrigeration cycle.

Reduce refrigerant until speci-
fied pressure is obtained.

Air suction by cooling fan is
insufficient.

Insufficient condenser cooling
performance.

↓

1. Condenser fins are clogged.

2. Improper fan rotation of

cooling fan.

●

Clean condenser.

●

Check and repair cooling fan
as necessary.

●

Low-pressure pipe is not
cold.

●

When compressor is
stopped high-pressure
value quickly drops by
approximately 196 kPa (2
kg/cm

2

, 28 psi). It then

decreases gradually there-
after.

Poor heat exchange in con-
denser
(After compressor operation
stops, high-pressure
decreases too slowly.).

↓

Air in refrigeration cycle.

Evacuate repeatedly and
recharge system.

Engine tends to overheat.

Engine cooling systems mal-
function.

Check and repair each engine
cooling system.

●

An area of the low-pres-
sure pipe is colder than
areas near the evaporator
outlet.

●

Low-pressure pipe is
sometimes covered with
frost.

●

Excessive liquid refrigerant
on low-pressure side.

●

Excessive refrigerant dis-
charge flow.

●

Expansion valve is open a
little compared with the
specification.

↓

Improper expansion valve
adjustment.

Replace expansion valve.

AC359A

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

High-pressure side is too high and
low-pressure side is too low.

Upper side of condenser and
high-pressure side are hot,
however, liquid tank is not so
hot.

High-pressure tube or parts
located between compressor
and condenser are clogged or
crushed.

●

Check and repair or replace
malfunctioning parts.

●

Check lubricant for contami-
nation.

AC360A

TROUBLE DIAGNOSIS

ATC-105

C

D

E

F

G

H

I

K

L

M

A

B

ATC

High-pressure Side is Too Low and Low-pressure Side is Too High

Both High- and Low-pressure Sides are Too Low

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

High-pressure side is too low and
low-pressure side is too high.

High- and low-pressure sides
become equal soon after com-
pressor operation stops.

Compressor pressure opera-
tion is improper.

↓

Damaged inside compressor
packings.

Replace compressor.

No temperature difference
between high- and low-pres-
sure sides.

Compressor pressure opera-
tion is improper.

↓

Damaged inside compressor
packings.

Replace compressor.

AC356A

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Both high- and low-pressure sides
are too low.

●

There is a big temperature
difference between liquid
tank outlet and inlet. Outlet
temperature is extremely
low.

●

Liquid tank inlet and expan-
sion valve are frosted.

Liquid tank inside is slightly
clogged.

●

Replace liquid tank.

●

Check lubricant for contami-
nation.

●

Temperature of expansion
valve inlet is extremely low
as compared with areas
near liquid tank.

●

Expansion valve inlet is
frosted.

●

Temperature difference
occurs somewhere in high-
pressure side.

High-pressure pipe located
between liquid tank and
expansion valve is clogged.

●

Check and repair malfunc-
tioning parts.

●

Check lubricant for contami-
nation.

Expansion valve and liquid
tank are warm or slightly cool
when touched.

Low refrigerant charge.

↓

Leaking fittings or compo-
nents.

Check refrigerant for leaks.
Refer to

ATC-169, "Checking

for Refrigerant Leaks"

.

There is a big temperature dif-
ference between expansion
valve inlet and outlet while the
valve itself is frosted.

Expansion valve closes a little
compared with the specifica-
tion.

↓

1. Improper expansion valve

adjustment.

2. Malfunctioning expansion

valve.

3. Outlet and inlet may be

clogged.

●

Remove foreign particles by
using compressed air.

●

Replace expansion valve.

●

Check lubricant for contami-
nation.

An area of the low-pressure
pipe is colder than areas near
the evaporator outlet.

Low-pressure pipe is clogged
or crushed.

●

Check and repair malfunc-
tioning parts.

●

Check lubricant for contami-
nation.

Air flow volume is not enough
or is too low.

Evaporator is frozen.

●

Check intake sensor circuit.
Refer to

ATC-121, "Intake

Sensor Circuit"

.

●

Replace compressor.

●

Repair evaporator fins.

●

Replace evaporator.

●

Refer to

ATC-88, "Blower

Motor Circuit"

.

AC353A

ATC-106

TROUBLE DIAGNOSIS

Low-pressure Side Sometimes Becomes Negative

Low-pressure Side Becomes Negative

DIAGNOSIS PROCEDURE FOR INSUFFICIENT COOLING

SYMPTOM: Insufficient cooling

1.

CHECK POWER SUPPLY FOR ECV (ELECTRONIC CONTROL VALVE)

1.

Disconnect compressor (ECV) connector.

2.

Turn ignition switch ON.

3.

Check voltage between compressor (ECV) harness connector
F34 terminal 2 and ground.

OK or NG

OK

>> GO TO 2.

NG

>> Check power supply circuit and 10A fuse [No. 12,

located in the fuse block (J/B)]. Refer to

PG-114, "FUSE

BLOCK - JUNCTION BOX (J/B)"

.

●

If fuse is OK, check harness for open circuit. Repair or replace if necessary.

●

If fuse is NG, check harness for short circuit and replace fuse.

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Low-pressure side sometimes
becomes negative.

●

Air conditioning system
does not function and does
not cyclically cool the com-
partment air.

●

The system constantly func-
tions for a certain period of
time after compressor is
stopped and restarted.

Refrigerant does not dis-
charge cyclically.

↓

Moisture is frozen at expan-
sion valve outlet and inlet.

↓

Water is mixed with refriger-
ant.

●

Drain water from refrigerant
or replace refrigerant.

●

Replace liquid tank.

AC354A

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Low-pressure side becomes nega-
tive.

Liquid tank or front/rear side of
expansion valve’s pipe is
frosted or wet with dew.

High-pressure side is closed
and refrigerant does not flow.

↓

Expansion valve or liquid tank
is frosted.

Leave the system at rest until
no frost is present. Start it
again to check whether or not
the malfunction is caused by
water or foreign particles.

●

If water is the cause, initially
cooling is okay. Then the
water freezes causing a
blockage. Drain water from
refrigerant or replace refrig-
erant.

●

If due to foreign particles,
remove expansion valve
and remove the particles
with dry and compressed air
(not shop air).

●

If either of the above meth-
ods cannot correct the mal-
function, replace expansion
valve.

●

Replace liquid tank.

●

Check lubricant for contami-
nation.

AC362A

2 – ground

: Battery voltage

RJIA4213E