K11 Service ManualK11

Torque Specs Tools Parts Diagrams

DIAGNOSES — Overall System / Performance Test Diagnoses (Cont'd) — TROUBLE DIAGNOSES FOR ABNORMAL PRESSURE

HA-34spec table

Continued from HA-33

Performance Test Diagnoses (Cont'd)

TROUBLE DIAGNOSES FOR ABNORMAL PRESSURE

Whenever abnormal pressure of high and/or low sides of the system is noted, diagnosis must be conducted by using a manifold gauge. The large-line zone on the gauge scale (see illustrations.) shown in the following table refers to the standard (normal) pressure range for the corresponding pressure side (high or low). Since the standard (normal) pressure, however, differs from vehicle to vehicle, refer to the "Ambient Temperature-Pressure Characteristics" chart.

Trouble diagnoses for abnormal pressure — Case A: Both high- and low-pressure sides are too high

Gauge indication	Refrigerant cycle	Probable cause	Corrective action
Both high- and low-pressure sides are too high. [A]	• Pressure is reduced soon after water is splashed on condenser. • No air bubbles appear in sight glass when pressure is reduced.	Excessive refrigerant charge in refrigeration cycle	Reduce refrigerant until specified pressure is obtained.
Both high- and low-pressure sides are too high. [A]	Air suction by radiator or condenser fan is insufficient.	Insufficient condenser cooling performance → ① Condenser fins are clogged. ② Improper rotation of radiator fan or condenser fan	• Clean condenser. • Check and repair radiator or condenser fan as necessary.
Both high- and low-pressure sides are too high. [A]	• Low-pressure pipe is not cold. • When compressor is stopped high-pressure value quickly drops by approximately 196 kPa (2.0 bar, 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.
Both high- and low-pressure sides are too high. [A]	Engine tends to overheat.	Engine cooling systems malfunction.	Check and repair each engine cooling system.
Both high- and low-pressure sides are too high. [A]	• Areas near low-pressure pipe connection and service valves are considerably cold compared with areas near expansion valve outlet or evaporator. • Plates are 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. → ① Improper thermal valve installation ② Improper expansion valve adjustment	Replace expansion valve.

Both high- and low-pressure sides are too high. [A]

Refrigerant cycle• Pressure is reduced soon after water is splashed on condenser. • No air bubbles appear in sight glass when pressure is reduced.

Probable causeExcessive refrigerant charge in refrigeration cycle

Corrective actionReduce refrigerant until specified pressure is obtained.

Both high- and low-pressure sides are too high. [A]

Refrigerant cycleAir suction by radiator or condenser fan is insufficient.

Probable causeInsufficient condenser cooling performance → ① Condenser fins are clogged. ② Improper rotation of radiator fan or condenser fan

Corrective action• Clean condenser. • Check and repair radiator or condenser fan as necessary.

Both high- and low-pressure sides are too high. [A]

Refrigerant cycle• Low-pressure pipe is not cold. • When compressor is stopped high-pressure value quickly drops by approximately 196 kPa (2.0 bar, 2 kg/cm², 28 psi). It then decreases gradually thereafter.

Probable causePoor heat exchange in condenser (After compressor operation stops, high pressure decreases too slowly.) → Air in refrigeration cycle

Corrective actionEvacuate repeatedly and recharge system.

Both high- and low-pressure sides are too high. [A]

Refrigerant cycleEngine tends to overheat.

Probable causeEngine cooling systems malfunction.

Corrective actionCheck and repair each engine cooling system.

Both high- and low-pressure sides are too high. [A]

Refrigerant cycle• Areas near low-pressure pipe connection and service valves are considerably cold compared with areas near expansion valve outlet or evaporator. • Plates are sometimes covered with frost.

Probable cause• Excessive liquid refrigerant on low-pressure side • Excessive refrigerant discharge flow • Expansion valve is open a little compared with the specification. → ① Improper thermal valve installation ② Improper expansion valve adjustment

Corrective actionReplace expansion valve.

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See also

Ambient Temperature-Pressure Characteristics chart