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WINDSHIELD FOGGED [CLIMATE CONTROL SYSTEM]

DESCRIPTION

  • A/C compressor does not operate while airflow mode is in DEFROSTER or DEF/HEAT modes

  • Air intake mode does not change to FRESH while airflow mode is in DEFROSTER or DEF/HEAT modes

POSSIBLE CAUSE

  • A/C compressor malfunction

  • INTERIOR 15 A fuse, ROOM 25 A malfunction

  • Air intake link malfunction

  • Open or short circuit in wiring harness between climate control unit and air intake actuator

  • Air intake actuator malfunction

  • Climate control unit malfunction

  • A/C unit malfunction

  • Air intake door malfunction

  • When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while doing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, inspect to make sure connectors, terminals and wiring harness are connected correctly and undamaged.

Diagnostic Procedure

Step

Inspection

Action

1

 COOL AIR BLOW OUT INSPECTION

  • When both the A/C switch and airflow volume control dial in the climate control unit are on, does cool air blow out from the vent?

Yes

Go to the next step.

No

Go to Step 1 of the following troubleshooting.

NO COOL AIR [CLIMATE CONTROL SYSTEM]

2

 INSPECT FUSE

  • Remove the INTERIOR 15 A fuse and ROOM 25 A fuse.

  • Is the fuse normal?

Yes

Go to the next step.

No

If the fuse is melted:

Repair or replace wiring harness for a short to ground and replace the fuse.

If the fuse is deterioration:

Replace the fuse.

Then go to Step 13.

3

 INSPECT AIR INTAKE ACTUATOR LINK

  • Inspect the air intake actuator link.

    (See A/C UNIT REMOVAL/INSTALLATION.)

    • Is there grease on the link?

    • Is the link securely and properly positioned?

    • Is the link free of obstructions?

  • Are the above items normal?

Yes

Go to the next step.

No

Apply grease or install the link properly and securely, remove obstruction, then go to Step 13.

(See A/C UNIT DISASSEMBLY/ASSEMBLY.)

4*

 INSPECT WIRING HARNESS BETWEEN FUSE BLOCK AND CLIMATE CONTROL UNIT FOR CONTINUITY

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between fuse block terminal and climate control unit terminal.

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness.

Go to Step 13.

5

 VERIFY WHETHER MALFUNCTION IS IN A/C UNIT AIR INTAKE DOOR OR ELSEWHERE

Yes

Go to the next step.

No

Go to Step 11.

6

 INSPECT AIR INTAKE ACTUATOR

Yes

Go to the next step.

No

Replace the air intake actuator, go to Step 13.

(See AIR INTAKE ACTUATOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)

(See AIR INTAKE ACTUATOR REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)

7

 INSPECT AIR INTAKE SELECTOR SWITCH AND DEFROSTER SWITCH IN CLIMATE CONTROL UNIT

  • Measure voltage at the following terminals of climate control unit.

    • Terminal U (FRESH signal)

    • Terminal S (RECIRCULATE signal)

  • Is voltage normal?

Yes

Go to the next step.

No

Replace the climate control unit, then go to Step 13.

(See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)

(See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)

8*

 INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR FOR CONTINUITY

  • Switch the ignition off.

  • Is there continuity between the following climate control unit terminals and air intake actuator terminals?

    • Terminal U —Terminal A (FRESH signal)

    • Terminal S —Terminal B (RECIRCULATE signal)

Yes

Go to the next step.

No

Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air intake actuator terminal.

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has an open circuit.

Go to Step 13.

9*

 INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR FOR SHORT TO GROUND

  • Is there continuity between the following climate control unit terminals and ground?

    • Terminal U (FRESH signal)

    • Terminal S (RECIRCULATE signal)

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air intake actuator terminal.

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to ground.

Go to Step 13.

No

Go to the next step.

10*

 INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR FOR SHORT TO B+

  • Switch the ignition ON (engine off or on).

  • Measure the voltage at the following climate control unit terminals.

    • Terminal U (FRESH signal)

    • Terminal S (RECIRCULATE signal)

  • Is the voltage approx. 12 V?

Yes

Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air intake actuator terminal.

    If there is a common connector:

  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to power supply.

  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to power supply.

Go to Step 13.

No

Replace the climate control unit, then go to Step 13.

(See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)

(See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)

11

 INSPECT A/C UNIT AIR INTAKE DOOR

Yes

Remove obstruction, then go to Step 13.

No

Go to the next step.

12

 VERIFY THAT A/C UNIT AIR INTAKE DOOR IS POSITIONED SECURELY AND PROPERLY

Yes

Go to the next step.

No

Install the air intake door securely in the proper position, then go to the next step.

(See A/C UNIT DISASSEMBLY/ASSEMBLY.)

13

 VERIFY THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR

  • Does the malfunction disappear?

Yes

Troubleshooting completed.

Explain repairs to customer.

No

Recheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.
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Free to use workshop manual for your 2015+ Mk4 'ND' Mazda MX-5

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