Rick's Free Auto Repair Advice

Diagnose Hyundai AC compressor with variable displacement and external control valve

Hyundai service bulletin #17-HA-002  for AC compressor with variable displacement and external control valve

Hyundai has issued a service bulletin #17-HA-002 to address an AC issue where:

• The AC does not get cold enough
• The high and/or low sides show abnormal system pressure on the manifold gauge (normal pressure should be > 130-psi at idle on the high side with AC set to MAX)

Diagnose AC problem with Hyundai AC compressor with variable displacement and external control valve

1. Start the engine, set the blower speed to level 2, and select MAX AC with the coldest temp setting.

2. Check the AC pressure. High side pressure must be above 130 PSI

3. If the high side pressure is below spec, inspect the limiter of the disc & hub assembly while rotating the engine.

To prevent AC drive belt disengagement in the event of a compressor seize, the compressor pulley contains a built-in torque limiter slip clutch. In the event the compressor seizes, the torque limiter slip clutch will shear off the engagement points, allowing the compressor pulley to continue to spin while no longer applying rotational force to the compressor input shaft.

clutchless AC compressor

How to check for a sheared torque limiter slip clutch

During normal operation, the center bolt at the front of the pulley will rotate at the same speed as the pulley. If the pulley spins but the center bolt does not, the torque limiter slip clutch has sheared due to internal binding and the compressor must be replaced.

If the center bolt is rotating, proceed with the diagnosis

Conduct the ECV resistance test

Using the diagnosis kit  in Hyundai part 00305

ACKIT TOOL , connect a multimeter  to leads

external control valve

External control valve

from the ECV and check resistance. The kit contains extension harnesses needed for testing. Normal ECV resistance should be 10.1 ~ 11.1Ω when the ambient temperature is 77°F. However, resistance may vary due to higher underhood temperatures. The acceptable range is (8 Ω ≤ ECV Resistance ≤ 14 Ω).

If the resistance is outside of the acceptable range, replace the ECV.

Conduct the AC pressure test

Using the test kit according to the instructions. Start the engine and set the blower to speed 2, with the selector set to MAX and engine at idle speed.

Turn the kit switch to the ON position and check AC pressures. Low side should show20 – 40psi, High side 130 – 190psi

Do NOT conduct this test for more than 30-seconds or you could experience evaporator core freeze up or expansion valve freeze up.

If the pressure are normal as shown above, check all the wiring to the AC heater control head. Repair any damaged wiring/connection.

If the pressures are out of specification, check the following:

• Check the radiator cooling fans for proper operation

• Evacuate the system and install the correct refrigerant charge.

• Check the AC lines, expansion valve, evaporator and condenser fins for blockage.

• Check the ECV valve for corroded, damaged or bent pins.

• Replace the ECV if not other faults are found.

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Posted on by Rick Muscoplat

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