Climate Control Unit Inspection (Auto A/C): Notes
WARNING: This page is about a different car, the 2020 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.
- Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
- Remove the following parts:
- Selector lever knob (AT) (See AUTOMATIC TRANSMISSION SHIFT MECHANISM REMOVAL/INSTALLATION .) (2) Shift lever knob (MT) (3) Shift panel component (See SHIFT PANEL REMOVAL/INSTALLATION .) (4) Upper panel (See UPPER PANEL REMOVAL/INSTALLATION .) (5) Parking brake lever boot panel (See PARKING BRAKE LEVER BOOT PANEL REMOVAL/INSTALLATION .) (6) Rear console (See REAR CONSOLE REMOVAL/INSTALLATION .) (7) Front console panel (See FRONT CONSOLE PANEL REMOVAL/INSTALLATION .) (8) Front console component (See FRONT CONSOLE REMOVAL/INSTALLATION .) (9) Scuff plate (See SCUFF PLATE REMOVAL/INSTALLATION .) (10) Front side trim (See FRONT SIDE TRIM REMOVAL/INSTALLATION .) (11) A-pillar trim (See A-PILLAR TRIM REMOVAL/INSTALLATION .) (12) Hood release lever (See HOOD RELEASE LEVER AND RELEASE CABLE REMOVAL/INSTALLATION .) (13) Driver-side lower panel (See DRIVER-SIDE LOWER PANEL REMOVAL/INSTALLATION .) (14) Passenger-side lower panel (See PASSENGER-SIDE LOWER PANEL REMOVAL/INSTALLATION .) (15) Center panel No. 1 (See CENTER PANEL No. 1 REMOVAL/INSTALLATION .)
- Remove the climate control unit with the connector connected. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION (AUTO A/C) .)
- Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION .)
- Switch the ignition ON (engine off or on).
- Connect the negative (-) lead of the tester to body ground.
- Insert the positive (+) lead of the tester into each climate control unit terminal and measure the voltage according to the terminal voltage table.
- If there is any malfunction, inspect the parts under "Inspection item(s)".
- If the parts under "Inspection item(s)" are found to be normal (except for terminal Q), replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION (AUTO A/C) .)
- For terminal Q, first try replacing the blower fan controller. If there is still any malfunction, replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION (AUTO A/C) .)
- If there is any malfunction, inspect the parts under "Inspection item(s)".
Terminal voltage table (reference)
| Terminal | Signal name | Connected to | Measurement condition | Voltage (V) | Inspection item(s) |
|---|---|---|---|---|---|
| A | - | - | - | - | - |
| B | MS_CAN_L | CAN related module | Because this terminal is for communication, integrity determination by terminal voltage is not possible. |
|
|
| C | GND | Body ground | Under any condition | 1.0 or less |
|
| D | MS_CAN_H | CAN related module | Because this terminal is for communication, integrity determination by terminal voltage is not possible. |
|
|
| E | Sensor GND |
|
Under any condition | 1.0 or less |
|
| F | Passenger compartment temperature sensor input | Passenger compartment temperature sensor | Compared with temperature detected by passenger compartment temperature sensor | Refer to graph 1 |
|
| G | Potentiometer input | Air mix actuator | Set temperature at HOT | 2.9 or more |
|
| Set temperature at COLD | 1.0 or less | ||||
| H | +5V |
|
Under any condition | 5 |
|
| I | Potentiometer input | Airflow mode actuator | VENT | 0.5 or less |
|
| BI-LEVEL | 1.45 | ||||
| HEAT | 2.44 | ||||
| HEAT/DEF | 3.44 | ||||
| DEFROSTER | 4.41 or more | ||||
| J | Evaporator temperature sensor input | Evaporator temperature sensor | Compared with temperature detected by evaporator temperature sensor | Refer to graph 2 |
|
| K | Solar radiation sensor input | Solar radiation sensor | Sunlight shined directly on solar radiation sensor | Voltage value is output |
|
| Blocking light to solar radiation sensor | 0 | ||||
| L | B+ |
|
Under any condition | B+ |
|
| M | - | - | - | - | - |
| N | IG1 |
|
Switch the ignition ON (engine off or on) | B+ |
|
| Switch the ignition off | 1.0 or less | ||||
| O | - | - | - | - | - |
| P | - | - | - | - | - |
| Q | Blower fan speed control | Blower fan controller | (See BLOWER FAN SPEED CONTROL SIGNAL .) |
|
|
| R | - | - | - | - | - |
| S | Motor operation (RECIRCULATE) | Air intake actuator | Moving towards RECIRCULATE | B+ |
|
| Moving towards FRESH | 1.0 or less | ||||
| T | Motor operation (VENT) | Airflow mode actuator | Moving towards VENT | B+ |
|
| Moving towards DEFROSTER | 1.0 or less | ||||
| U | Motor operation (FRESH) | Air intake actuator | Moving towards RECIRCULATE | 1.0 or less |
|
| Moving towards FRESH | B+ | ||||
| V | Motor operation (DEFROSTER) | Airflow mode actuator | Moving towards DEFROSTER | B+ |
|
| Moving towards VENT | 1.0 or less | ||||
| W | Motor operation (COLD) | Air mix actuator | Moving towards HOT | 1.0 or less |
|
| Moving towards COLD | B+ | ||||
| X | Motor operation (HOT) | Air mix actuator | Moving towards HOT | B+ |
|
| Moving towards COLD | 1.0 or less | ||||