Symptom Table

WARNING: This page is about a different car, the 2013 Infiniti FX50. However, it is still accessible from the selected car via links, so may be relevant.

Gauge indication	Refrigerant cycle	Probable cause	Corrective action
Both high- and low-pressure sides are too high.	The pressure returns to normal is reduced soon after water is splashed on condenser.	Excessive refrigerant charge in refrigeration cycle.	Reduce refrigerant until specified pressure is obtained.
	Air suction by cooling fan is insufficient.	Insufficient condenser cooling performance. ↓ Condenser fins are clogged. Improper fan rotation of cooling fan.	Clean condenser. Check and repair cooling fan if necessary.
	Low-pressure pipe is not cold. When compressor is stopped, high-pressure reading quickly drops by approximately 196 kPa (2 kg/cm² , 28 psi). It then decreases gradually thereafter.	Poor heat exchange in condenser (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 malfunction.	Check and repair each engine cooling system.
	An area of the low-pressure 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 discharge flow. Expansion valve is open a little compared with the specification. ↓ Improper expansion valve adjustment.	Replace expansion valve.
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 contamination.
High-pressure side is too low and low-pressure side is too high.	High- and low-pressure sides become equal soon after compressor operation stops.	Compressor pressure operation is improper. ↓ Damaged inside compressor packings.	Replace compressor.
	No temperature difference between high- and low-pressure sides.	Compressor pressure operation is improper. ↓ Damaged inside compressor packings.	Replace compressor.
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 expansion valve are frosted.	Liquid tank inside is slightly clogged.	Replace liquid tank. Check lubricant for contamination.
	Expansion valve inlet temperature 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 malfunctioning parts. Check lubricant for contamination.
	Expansion valve and liquid tank are warm or slightly cool when touched.	Low refrigerant charge. ↓ Leaking fittings or components.	Check refrigerant for leakages. Refer to "REFRIGERANT LEAKAGES ".
	There is a big temperature difference between expansion valve inlet and outlet while the valve itself is frosted.	Expansion valve closes a little compared with the specification. ↓ Improper expansion valve adjustment. Malfunctioning expansion valve. Outlet and inlet may be clogged.	Remove foreign particles by using compressed air. Replace expansion valve. Check lubricant 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 malfunctioning parts. Check lubricant for contamination.
	Air flow volume is not enough or is too low.	Evaporator is frozen.	Check intake sensor circuit. Refer to "DIAGNOSIS PROCEDURE ". Replace compressor. Repair evaporator fins. Replace evaporator. Check blower motor circuit. Refer to "DIAGNOSIS PROCEDURE ".
Low-pressure side sometimes becomes negative.	Air conditioning system does not function and does not cyclically cool the compartment air. The system constantly functions for a period of time after compressor is stopped and restarted.	Refrigerant does not discharge cyclically. ↓ Moisture is frozen at expansion valve outlet and inlet. ↓ Water is mixed with refrigerant.	Drain water from refrigerant or replace refrigerant. Replace liquid tank.
Low-pressure side becomes negative.	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. Cooling is initially okay if water is the cause. Then the water freezes causing a blockage. Drain water from refrigerant or replace refrigerant. Remove expansion valve and remove the particles with dry and compressed air (not shop air) if due to foreign particles. Replace expansion valve if either of the above methods cannot correct the malfunction. Replace liquid tank. Check lubricant for contamination.