Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

NO TEMPERATURE CONTROL WITH CLIMATE CONTROL UNIT (FULL-AUTO AIR CONDITIONER) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	INSPECT COOLANT TEMPERATURE Is the coolant sufficiently warmed up?	Yes	Go to the next step.
1		No	Warm up the engine, then go to Step 24.
2*	INSPECT FUSE Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Remove the ROOM 15 A fuse. Is the fuse normal?	Yes	Go to the next step.
2*		No	If the fuse is blown: Refer to the wiring diagram and verify whether or not there is a common connector between ROOM 15 A fuse 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 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. Replace the fuse. If the fuse is damaged: Replace the fuse. Then go to Step 24.
3*	INSPECT TO SEE WHETHER MALFUNCTION (OPEN CIRCUIT) IS IN B+ SIGNAL WIRING HARNESS (BETWEEN FUSE BLOCK AND CLIMATE CONTROL UNIT) OR ELSEWHERE Disconnect the climate control unit connector. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure voltage at the following terminal (wiring harness-side). With dual type climate control unit: Climate control unit terminal 1B With single type climate control unit: Climate control unit terminal L Is the voltage B+?	Yes	Go to the next step.
3*		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 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 24.
4*	INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT OR AIR MIX ACTUATOR Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Connect the climate control unit connector. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure and record the voltage at the following terminals (wiring harness-side) when temperature setting to MAX HOT and MAX COLD. With dual type climate control unit: Climate control unit terminal 2G Climate control unit terminal 2E With single type climate control unit: Climate control unit terminal G Are voltages normal?	Yes	Go to Step 22.
4*		No	Go to the next step.
5*	INSPECT TO SEE WHETHER MALFUNCTION IS IN POSITION SENSOR OR ELSEWHERE Measure voltage at the following terminal (wiring harness-side) when airflow mode at VENT and DEFROSTER. With dual type climate control unit: Climate control unit terminal 2A With single type climate control unit: Climate control unit terminal I Is voltage normal?	Yes	Go to Step 8.
5*		No	Go to the next step.
6*	INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO BATTERY POWER OR GROUND) IS IN POSITION SENSOR POWER SUPPLY OR ELSEWHERE Measure voltage at the following terminal (wiring harness-side). With dual type climate control unit: Climate control unit terminal 1N With single type climate control unit: Climate control unit terminal H Is voltage approx. 5 V?	Yes	Go to the next step.
6*		No	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and each actuator/sensor 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 24.
7*	INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO POWER SUPPLY) IS IN POSITION SENSOR GROUND OR ELSEWHERE Measure voltage at the following terminal (wiring harness-side). With dual type climate control unit: Climate control unit terminal 1J With single type climate control unit: Climate control unit terminal E Is the voltage below 1.0 V?	Yes	Refer to wiring diagram and inspect for open circuit following. With dual type climate control unit: Between climate control unit terminal 1N and junction point to actuators/sensors (position sensor power supply). Between climate control unit terminal 1J and junction point to actuators/sensors (position sensor ground). With single type climate control unit: Between climate control unit terminal H and junction point to actuators/sensors (position sensor power supply). Between climate control unit terminal E and junction point to actuators/sensors (position sensor ground). Repair or replace the malfunctioning part or wiring harness. Go to Step 24.
7*		No	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and each actuator/sensor 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 24.
8	INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO POWER SUPPLY) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR ELSEWHERE Is the voltage B+, at Step 4?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air mix 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 24.
8		No	Go to the next step.
9	INSPECT CLIMATE CONTROL UNIT CONNECTOR CONNECTION CONDITION Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Inspect the climate control unit connector engagement and connection condition. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Is the connector normal?	Yes	Go to the next step.
9		No	Reconnect the climate control unit connector properly. Go to Step 24.
10	INSPECT CLIMATE CONTROL UNIT CONNECTOR TERMINAL CONDITION Disconnect the climate control unit connector. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Inspect the connector and terminals (corrosion, damage, pin disconnection). Are the connector and terminals normal?	Yes	Go to the next step.
10		No	Repair/replace the connector or terminal. Go to Step 24.
11	INSPECT AIR MIX ACTUATOR CONNECTOR CONNECTION CONDITION Inspect the air mix actuator connector engagement and connection condition. (See AIR MIX ACTUATOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Is the connector normal?	Yes	Go to the next step.
11		No	Reconnect the air mix actuator connector properly. Go to Step 24.
12	INSPECT AIR MIX ACTUATOR CONNECTOR TERMINAL CONDITION Disconnect the air mix actuator connector. (See AIR MIX ACTUATOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Inspect the connector and terminals (corrosion, damage, pin disconnection). Are the connector and terminals normal?	Yes	Go to the next step.
12		No	Repair/replace the connector or terminal. Go to Step 24.
13*	INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR ELSEWHERE Inspect continuity between the following terminals (wiring harness-side): With dual type climate control unit: - Climate control unit terminal 2G-air mix actuator terminal F Climate control unit terminal 2E-air mix actuator terminal F With single type climate control unit: Climate control unit terminal G- air mix actuator terminal F Is there continuity?	Yes	Go to the next step.
13*		No	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air mix 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. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness. Go to Step 24.
14*	INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO GROUND) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR ELSEWHERE Inspect for continuity between the following terminals (wiring harness-side) and body ground: With dual type climate control unit: Climate control unit terminal 2G Climate control unit terminal 2E With single type climate control unit: Climate control unit terminal G Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and each side air mix 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. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness. Go to Step 24.
14*		No	Go to the next step.
15*	INSPECT TO SEE WHETHER MALFUNCTION (OPEN CIRCUIT) IS IN POSITION SENSOR POWER SUPPLY OR ELSEWHERE Inspect for continuity between the following terminals (wiring harness-side) and junction point to other actuators/sensors (position sensor power supply). With dual type climate control unit: Driver-side air mix actuator terminal G Passenger-side air mix actuator terminal E With single type climate control unit: Air mix actuator terminal E Is there continuity?	Yes	Go to the next step.
15*		No	Refer to the wiring diagram and verify whether or not there is a common connector between air mix actuator terminal and junction point to other actuators/sensor 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 24.
16*	INSPECT TO SEE WHETHER MALFUNCTION (OPEN CIRCUIT) IS IN POSITION SENSOR GROUND OR ELSEWHERE Inspect for continuity between the following terminals (wiring harness-side) and junction point to other actuators/sensors (position sensor ground). With dual type climate control unit: - Driver-side air mix actuator terminal E Passenger-side air mix actuator terminal G With single type climate control unit: Air mix actuator terminal G Is there continuity?	Yes	Go to the next step.
16*		No	Refer to the wiring diagram and verify whether or not there is a common connector between air mix actuator terminal and junction point to other actuators/sensor 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 24.
17*	INSPECT TO SEE WHETHER MALFUNCTION IS IN AIR MIX ACTUATOR OR WIRING HARNESS (LACK OF CONTINUITY BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) Connect the climate control unit connector. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure voltage at the following terminals (wiring harness-side). With dual type climate control unit: Driver-side air mix actuator terminal B (HOT motor drive signal) Driver-side air mix actuator terminal C (COLD motor drive signal) Passenger-side air mix actuator terminal C (HOT motor drive signal) Passenger-side air mix actuator terminal B (COLD motor drive signal) With single type climate control unit: Air mix actuator terminal C (HOT motor drive signal) Air mix actuator terminal B (COLD motor drive signal) Are voltages normal?	Yes	Go to Step 21.
17*		No	Go to the next step.
18*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY OR OPEN BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE Switch the ignition off. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Disconnect the climate control unit connector. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Inspect for continuity between the following terminals (wiring harness-side). With dual type climate control unit: Climate control unit terminal 2D-driver-side air mix actuator terminal B (HOT motor drive signal) Climate control unit terminal 2B-driver-side air mix actuator terminal C (COLD motor drive signal) Climate control unit terminal 2F- passenger-side air mix actuator terminal C (HOT motor drive signal) Climate control unit terminal 2H-passenger-side air mix actuator terminal B (COLD motor drive signal) With single type climate control unit: Climate control unit terminal X-air mix actuator terminal C (HOT motor drive signal) Climate control unit terminal W- air mix actuator terminal B (COLD motor drive signal) Is there continuity?	Yes	Go to the next step.
18*		No	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air mix 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. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness. Go to Step 24.
19*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO B+ BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE Climate control unit and air mix actuator connectors are disconnected. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Switch the ignition ON (engine off or on). Measure voltage at the following terminals (wiring harness-side). With dual type climate control unit: Climate control unit terminal 2D (driver-side HOT motor drive signal) Climate control unit terminal 2B (driver-side COLD motor drive signal) Climate control unit terminal 2F (passenger-side HOT motor drive signal) Climate control unit terminal 2H (passenger-side COLD motor drive signal) With single type climate control unit: Climate control unit terminal X (HOT motor drive signal) Climate control unit terminal W (COLD motor drive signal) Are voltages approx. 0 V?	Yes	Go to the next step.
19*		No	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air mix 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 24.
20*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO GROUND BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE Switch the ignition off. Climate control unit and air mix actuator connectors disconnected. Inspect for continuity between the following terminals (wiring harness-side) and body ground. With dual type climate control unit: Climate control unit terminal 2D (driver-side HOT motor drive signal) Climate control unit terminal 2B (driver-side COLD motor drive signal) Climate control unit terminal 2F (passenger-side HOT motor drive signal) Climate control unit terminal 2H (passenger-side COLD motor drive signal) With single type climate control unit: Climate control unit terminal X (HOT motor drive signal) Climate control unit terminal W (COLD motor drive signal) Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between climate control unit terminal and air mix 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 24.
20*		No	Go to the next step.
21	INSPECT AIR MIX ACTUATOR Inspect the air mix actuator. (See AIR MIX ACTUATOR INSPECTION [FULL-AUTO AIR CONDITIONER] .) Is air mix actuator normal?	Yes	Replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Go to Step 24.
21		No	Replace the suspected side air mix actuator. (See AIR MIX ACTUATOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) Then go to Step 24.
22	INSPECT AIR MIX LINK Inspect the air mix links for each-side. (See A/C UNIT DISASSEMBLY/ASSEMBLY .) Is grease on link? Are links securely and properly installed? Are links free of obstructions and hindrances? Are the above items normal?	Yes	Go to the next step.
22		No	Apply grease to links. If any links are damaged. Replace malfunctioning part. (See A/C UNIT REMOVAL/INSTALLATION .) Then go to Step 24.
23	INSPECT A/C UNIT AND AIR MIX DOOR Inspect the A/C unit and each-side air mix door. (See A/C UNIT REMOVAL/INSTALLATION .) Is door free of obstructions and damage? Are doors securely and properly installed? Are the above items normal?	Yes	Inspect the heater hoses. If the heater hoses are not free of damage and cracks, repair or replace the heater hoses. If the heater hose connections are loose, install securely in correct position. Go to the next step.
23		No	Remove the obstruction, or install door in proper position. If any doors are cracked, replace them. (See A/C UNIT REMOVAL/INSTALLATION .) Then go to the next step.
24	VERIFY THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR Does the unit operate at every temperature setting?	Yes	Troubleshooting completed. Explain repairs to customer.
24		No	Recheck malfunction symptoms, then repeat from Step1 if the malfunction recurs.