Heater & Air Conditioning System: Diagnosis Nissan Note E12

Trouble Diagnosis For Unusual Pressure

Diagnose using a manifold gauge set whenever refrigerant pressures are unusual. The marker above the gauge scale in the following table indicates the standard (usual) pressure range. Refer to " INSPECTION ".

Symptom Table

Gauge indication Refrigerant cycle Probable cause Corrective action Both high and low-pressure sides are too high. The pressure returns to normal soon after sprinkling water on condenser. Overfilled refrigerant. Recover refrigerant, evacuate system, and recharge with the specified amount of refrigerant. Refer to " RECYCLE REFRIGERANT ". Air flow to condenser is insufficient. Insufficient condenser cooling performance. Poor cooling fan rotation. Missing and/or improper installation of air guides. Clogged or dirty condenser fins. Repair or replace malfunctioning parts. Clean and/or repair condenser fins. When compressor stops, high-pressure gauge quickly drops by approximately 196 kPa (2 kg/cm 2 , 28 psi), then gradually decreases. Air mixed with refrigerant. Recover refrigerant, evacuate system, and recharge with the specified amount of refrigerant. Refer to " RECYCLE REFRIGERANT ". Low-pressure pipe is cooler than the outlet of evaporator. Low-pressure pipe is frosted. Expansion valve opened too much (excessive flow of refrigerant). Replace expansion valve. Refer to " EXPANSION VALVE: REMOVAL AND INSTALLATION ". High-pressure side is excessively high and low-pressure side is too low. High-pressure pipe and upper side of condenser become hot, however, liquid tank does not become so hot. Clogged or crushed high-pressure pipe located between compressor and condenser. Repair or replace the malfunctioning parts. High-pressure side is too low and low-pressure side is too high. The readings of both sides become equal soon after compressor stops. There is no temperature difference between high and low-pressure sides. Malfunctioning compressor (insufficient compressor pressure operation). Damaged or broken of internal components. Malfunctioning gaskets. Replace compressor. Refer to " REMOVAL AND INSTALLATION ". Both high and low-pressure sides are too low. The area around evaporator outlet does not become cold. The area around evaporator inlet becomes frosted. Clogged expansion valve. Breakage of temperature sensor. Clogging by foreign material. Eliminate foreign material from expansion valve, or replace it. There is a temperature difference between the areas around outlet and inlet pipes of liquid tank. Liquid tank becomes frosted. Malfunction inside liquid tank (clogged strainer). Replace condenser (includes liquid tank). Refer to " CONDENSER: REMOVAL AND INSTALLATION ". Evaporator becomes frosted. Clogged or crushed low-pressure pipe. Repair or replace malfunctioning parts. Malfunctioning thermo amp. Check thermo amp. system. Refer to " COMPONENT PARTS LOCATION ". There is a small temperature difference between the high and low pressure pipes. Low refrigerant charge. Leak or leaks in A/C system. Check for leaks. Refer to " LEAK TEST ". Recover refrigerant, evacuate system, and recharge with the specified amount of refrigerant. Refer to " RECYCLE REFRIGERANT ". Low-pressure side sometimes becomes negative. Sometimes the area around evaporator outlet does not become cold. Sometimes the area around evaporator inlet is frosted. Icing caused by moisture mixed with refrigerant. Deteriorated dryer material in liquid tank. Recover refrigerant then replace condenser (includes liquid tank). Refer to " CONDENSER: REMOVAL AND INSTALLATION ". Evacuate system and recharge with the specified amount of refrigerant. Refer to " CHARGE REFRIGERANT "

Scheme 1

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Scheme 6

Scheme 7

1. Install a fender cover (1).
2. Wear UV safety goggles (2) provided with refrigerant dye leak detection kit.
3. Connect power cable (4) of UV lamp (6) to positive and negative terminals of the battery (3).
4. Press UV lamp switch (5) and check A/C system for refrigerant leaks. (Where refrigerant leaks occur, fluorescent leak detection dye appears green in color.) WARNING: Do not look directly into UV lamp light source. NOTE: For continuous operating time of UV lamp, follow the manufacturer's operating instructions. Illuminate pipe joints from different angles using UV lamp to check for leaks. Use a mirror in areas that are difficult to see to check for leaks. Refrigerant leaks from the evaporator can be detected by soaking a cotton swab or similar material with drain hose water and illuminating it using the UV lamp. Dust, dirt, and packing material adhesives used for condenser, evaporator, and other components may fluoresce. Be careful not to misidentify leaks.
5. Repair or replace parts where refrigerant leaks occur and wipe off fluorescent leak detection dye. NOTE: Completely wipe off fluorescent leak detection dye from gaps between parts, screw threads, and other components using a cotton swab or similar material.
6. Use a UV lamp to check that no fluorescent leak detection dye remains after finishing work. WARNING: Do not look directly into UV lamp light source. NOTE: For continuous operating time of UV lamp, follow the manufacturer's operating instructions. Dust, dirt, and packing material adhesives used for condenser, evaporator, and other components may fluoresce. Be careful not to misidentify leaks.

Inspection

If a compressor is malfunctioning (internal noise, insufficient cooling), check the compressor oil.

Scheme 8

1. COMPRESSOR OIL JUDGMENT Remove the compressor. Refer to " «REMOVAL AND INSTALLATION»(ref-675574-S28797984122014120500000) ". Sample the compressor oil and judge on the figure. Judgement result 1: Replace compressor only. Judgement result 2: Replace compressor and condenser (includes liquid tank).

INSPECTION PROCEDURE

1. Connect recovery/recycling/recharging equipment (for HFC-134a) or manifold gauge set.
2. Start the engine, and set to the following condition. TEST CONDITION Surrounding condition In a well-ventilated place away from direct sunlight. Vehicle condition Doors Closed Door glass Closed Hood Open Engine speed Idle speed A/C condition (front/rear) Temperature control Full cold A/C switch ON Air outlet VENT (ventilation) Intake door position Recirculation Blower speed Maximum
3. Maintain test condition until A/C system becomes stable. (Approximately 10 minutes)
4. Check that test results of "recirculating-to-discharge air temperature" and "ambient air temperature-to-operating pressure" are within the specified value.
5. When test results are within the specified value, inspection is complete. If any test result is out of the specified value, perform diagnosis by manifold gauge set. Refer to " «SYMPTOM TABLE»(ref-675574-S41224776252014120500000) ".