Nissan Titan. Manual - part 417

INSUFFICIENT COOLING

HAC-173

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

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Both High- and Low-pressure Sides are Too Low

Low-pressure Side Sometimes Becomes Negative

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 be-
tween high- and low-pressure 
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 oil for contamination.

• Temperature of expansion 

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

• Expansion valve inlet may 

be frosted.

• Temperature difference oc-

curs somewhere in high-
pressure side.

High-pressure pipe located be-
tween liquid tank and expan-
sion valve is clogged.

• Check and repair malfunc-

tioning parts.

• Check oil for contamination.

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

Low refrigerant charge.
↓
Leaking fittings or compo-
nents.

Check refrigerant system for 
leaks. Refer to 

HA-24, "Check-

ing of Refrigerant Leaks"

 or 

HA-26, "Checking of Refriger-
ant 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.

• Check oil for contamination.

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 oil for contamination.

Air flow volume is too low.

Evaporator is frozen.

• Check intake sensor circuit.

Refer to 

HAC-147, "Intake 

Sensor Diagnosis Proce-
dure"

.

• Repair evaporator fins.
• Replace evaporator.
• Refer to 

HAC-131, "Front 

Blower Motor Component 
Function Check"

.

AC353A

HAC-174

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

INSUFFICIENT COOLING

Low-pressure Side Becomes Negative

Gauge indication

Refrigerant cycle

Probable cause

Corrective action

Low-pressure side sometimes be-
comes negative.

• Air conditioning system does 

not function and does not cy-
clically cool the compart-
ment air.

• The system constantly func-

tions for a certain period of 
time after compressor is 
stopped and restarted.

Refrigerant does not discharge 
cyclically.
↓
Moisture is frozen at expan-
sion valve outlet and inlet.
↓
Water is mixed with refrigerant.

• 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 frost-

ed or dewed.

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 wa-
ter freezes causing a block-
age. Drain water from 
refrigerant or replace refrig-
erant.

• If due to foreign particles, re-

move 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 oil for contamination.

AC362A

INSUFFICIENT HEATING

HAC-175

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

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INSUFFICIENT HEATING

Component Function Check

INFOID:0000000009882555

SYMPTOM: Insufficient heating

INSPECTION FLOW

1.

CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - TEMPERATURE INCREASE 

1. Turn the blower control dial to low speed.

2. Turn the temperature control dial clockwise to maximum heat

3. Check for hot air at discharge air outlets.
Can this symptom be duplicated?

YES

>> GO TO 2. 

NO

>> Perform complete system operational check. Refer to 

HAC-99, "Operational Check"

.

2.

CHECK FOR SERVICE BULLETINS

Check for any service bulletins.

>> If equipped with NAVI, GO TO 3.

>> If not equipped with NAVI, GO TO 4.

3.

PERFORM SELF-DIAGNOSIS

Perform self-diagnosis. Refer to 

HAC-114, "Front Air Control Self-Diagnosis"

.

Is the inspection results normal?

YES

>> GO TO 4.

NO

>> Refer to 

HAC-166, "Symptom Matrix Chart"

.

4.

CHECK ENGINE COOLING SYSTEM

1. Check for proper engine coolant level. Refer to 

CO-10, "Inspection"

.

2. Check hoses for leaks or kinks.

3. Check radiator cap. Refer to 

CO-10, "Inspection"

.

4. Check for air in cooling system.

>> GO TO 5.

5.

CHECK AIR MIX DOOR OPERATION 

Check the operation of the air mix door.
Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Check the air mix door motor circuit. Refer to 

HAC-120, "Air Mix Door Motor Component Function

Check"

.

6.

CHECK AIR DUCTS 

Check for disconnected or leaking air ducts.
Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Repair all disconnected or leaking air ducts.

7.

CHECK HEATER HOSE TEMPERATURES

1. Start engine and warm it up to normal operating temperature.

2. Touch both the inlet and outlet heater hoses. The inlet hose should be hot and the outlet hose should be

warm.

Is the inspection result normal?

YES

>> Hot inlet hose and a warm outlet hose: GO TO 8.

NO

>> • Inlet hose cold: GO TO 11.

• Both hoses warm: GO TO 9.

HAC-176

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

INSUFFICIENT HEATING

8.

CHECK ENGINE COOLANT SYSTEM 

Check engine control temperature sensor. Refer to 

EC-191, "Component Inspection"

.

Is the inspection result normal?

YES

>> System OK.

NO

>> Repair or replace as necessary. Retest.

9.

CHECK HEATER HOSES 

Check heater hoses for proper installation.
Is the inspection result normal?

YES

>> System OK.

NO

>> 1. Back flush heater core. 

2. Drain the water from the system.   

3. Refill system with new engine coolant. Refer to 

CO-11, "Changing Engine Coolant"

. 

4. GO TO 10 to retest. 

10.

CHECK HEATER HOSE TEMPERATURES

1. Start engine and warm it up to normal operating temperature.

2. Touch both the inlet and outlet heater hoses. The inlet hose should be hot and the outlet hose should be

warm.

Is the inspection result normal?

YES

>> System OK.

NO

>> Replace heater core. Refer to 

VTL-15, "Removal and Installation"

.

11.

CHECK WATER VALVE

Check the operation of the water valve. Refer to 

HAC-142, "Water Valve Diagnosis Procedure"

.

Is the inspection result normal?

YES

>> System OK.

NO

>> Replace water valve.