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2008 - MX-5 - Engine

NO.23 A/C DOES NOT WORK SUFFICIENTLY [LF]



23

A/C DOES NOT WORK SUFFICIENTLY.

DESCRIPTION

A/C compressor magnetic clutch does not engage when the A/C switch is turned on.

POSSIBLE CAUSE

  • Improper refrigerant charging amount

  • Open the A/C magnetic clutch

  • Open circuit in wiring harness between A/C relay and A/C magnetic clutch

  • Poor GND of A/C magnetic clutch

  • Refrigerant pressure switch is stuck open.

  • A/C relay is stuck open.

  • Seized A/C compressor

  • Open circuit in wiring harness between A/C switch and PCM through both refrigerant pressure switch and A/C amplifier


Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1

Connect the M-MDS to the DLC-2.

Turn the ignition switch to the ON position (Engine off).

Retrieve any DTCs.

Are there any DTCs displayed?

Yes

DTC is displayed:

Go to the appropriate DTC inspection.

(See DTC TABLE [LF].)

No

No DTC is displayed:

Go to the next step.

2

Disconnect A/C compressor connector.

Start engine and turn A/C switch on.

Is there correct voltage at A/C compressor magnetic clutch terminal?

    Specification
  • 10.5 V or more

Yes

Inspect for GND condition of magnetic clutch on A/C compressor.

If GND condition is normal, inspect for open circuit magnetic clutch coil.

No

Go to the next step.

3

Disconnect refrigerant pressure switch connector.

Connect jumper wiring between A/C high pressure switch terminal.

Connect jumper wiring between refrigerant pressure switch terminal.

Turn the ignition switch to the ON position.

Turn A/C switch on and set blower fan to any speed.

Does A/C work?

Yes

Inspect refrigerant pressure switch operation.

If switch is normal, go to the next step.

No

Inspect for the following:

  • A/C switch is stuck open.

  • Open circuit in wiring harness between refrigerant pressure switch and PCM terminal 1AU

  • Open circuit in wiring harness between blower motor fan switch and resistor (if blower motor does not operate)

  • Evaporator temperature sensor and A/C amplifier

4

Remove jumper wiring from the switch connector.

Reconnect connector to refrigerant pressure switch.

Start the engine and turn the A/C switch on.

Does the fan operate?

Yes

Inspect whether A/C relay is stuck open.

Replace if necessary.

No

Inspect the following and repair or replace if necessary:

  • Refrigerant charging amount

  • A/C compressor for seizure

5

  • Verify test results.

    • If normal, return to diagnostic index to service any additional symptoms.

      (See SYMPTOM DIAGNOSTIC INDEX [LF].)

    • If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.

      • If vehicle is repaired, troubleshooting completed.

      • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM.

        (See PCM REMOVAL/INSTALLATION [LF].)




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