Nissan Frontier. Manual - part 899

HAC-150

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

INSUFFICIENT COOLING

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-151

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

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INSUFFICIENT HEATING

Component Function Check

INFOID:0000000009478366

SYMPTOM: Insufficient heating

INSPECTION FLOW

1.

CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - TEMPERATURE INCREASE 

1. Rotate blower control dial clockwise.

2. Turn the temperature control dial clockwise to maximum heat.

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

YES

>> GO TO 2. 

NO

>> Perform complete operational check. Refer to 

HAC-90, "Operational Check"

.

2.

CHECK FOR SERVICE BULLETINS

Check for any service bulletins.

>> GO TO 3.

3.

PERFORM SELF-DIAGNOSIS

Perform self-diagnosis. Refer to 

HAC-101, "Front Air Control Self-Diagnosis"

.

Is the inspection results normal?

YES

>> GO TO 4.

NO

>> Refer to 

HAC-142, "Symptom Matrix Chart"

.

4.

CHECK ENGINE COOLING SYSTEM

1. Check for proper engine coolant level. Refer to 

CO-11, "System Inspection"

 (QR25DE) or 

CO-39, "System

Inspection"

 (VQ40DE).

2. Check hoses for leaks or kinks.

3. Check radiator cap. Refer to 

CO-11, "System Inspection"

 (QR25DE) or 

CO-39, "System Inspection"

(VQ40DE).

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-108, "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

>> Both hoses warm: GO TO 9.

HAC-152

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

INSUFFICIENT HEATING

8.

CHECK ENGINE COOLANT SYSTEM 

Check engine coolant temperature sensor. Refer to 

EC-183, "Component Inspection"

 (QR25DE) or 

EC-652,

"Component Inspection"

 (VQ40DE).

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-12, "Changing Engine Coolant"

(QR25DE) or 

CO-40, "Changing Engine Coolant"

 (VQ40DE). 

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-19, "Removal and Installation"

.

NOISE

HAC-153

< SYMPTOM DIAGNOSIS >

[MANUAL A/C (TYPE 1)]

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NOISE

Component Function Check

INFOID:0000000009478367

SYMPTOM: Noise

INSPECTION FLOW

AWIIA1001GB