Nissan Sentra B18 (2020-2025) Service Manual: Symptom Table

Both high and low pressure sides are too high.

The pressure returns to normal soon after sprinkling water on condenser.

Overfilled refrigerant.

Collect all refrigerant, evacuate refrigerant cycle again, and then refill it with the specified amount of refrigerant.

Air flow to condenser is insufficient.

Insufficient condenser cooling performance.

• Poor fan rotation of radiator and condenser.

• Improper installation of air guide.

• Clogged or dirty condenser fins.

• Repair or replace malfunctioning parts.

• Clean and repair condenser fins.

When A/C compressor is stopped, a high-pressure reading quickly drops by approximately 196 kPa (2 kg/cm², 28 psi). It then gradually decreases.

Air mixed in refrigerant cycle.

Collect all refrigerant, evacuate refrigerant cycle again, and then refill it with the specified amount of 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.

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 A/C 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 A/C compressor operation stops.

• There is no temperature difference between high- and low-pressure sides.

Malfunction in A/C compressor system (insufficient A/C compressor pressure operation).

• Damage or breakage of valve.

• Malfunctioning gaskets.

Replace A/C compressor.

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 in inner liquid tank (clogged strainer).

Replace liquid tank.

Evaporator becomes frosted.

Clogged or crushed low-pressure pipe.

Repair or replace malfunctioning parts.

Malfunction in intake air temperature sensor.

Check intake sensor system. Refer to Diagnosis Procedure (automatic A/C) or Component Inspection (manual A/C).

There is a small temperature difference between the high and low pressure pipes for refrigerant cycle.

• Shortage of refrigerant.

• Leakage of refrigerant.

• Check for leakage.

• Collect all refrigerant, evacuate refrigerant cycle again, and then refill it with the specified amount of 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 the mixing of water in cooler cycle.

• Deteriorated dryer in liquid tank.

• Collect all refrigerant.

• Evacuate refrigerant cycle completely, and then refill it with the specified amount of refrigerant. At this time, always replace liquid tank.

Hunting in high-pressure side.

There is no temperature difference between high- and low-pressure sides.

Malfunctioning variable valve in A/C compressor.

• Replace A/C compressor.

• Check ECV system.