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.

AMOUNT OF AIR BLOWN FROM VENTS DOES NOT CHANGE (FULL-AUTO AIR CONDITIONER) - DIAGNOSTIC PROCEDURE

Step	Inspection		Action
1	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 HEATER 40 A fuse. Is the fuse normal?	Yes	Go to the next step.
1		No	If the fuse is blown: Refer to the wiring diagram and verify whether or not there is a common connector between HEATER 40 A fuse and blower fan controller terminal/front body control module (FBCM) 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 18.
2	INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER UNIT OR ELSEWHERE 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). Turn the airflow volume control switch on. Recirculate air inside the vehicle. Does the blower motor rotate?	Yes	Go to the next step.
2		No	Go to Step 4.
3	INSPECT BLOWER UNIT INTAKE VENT Is blower unit intake vent restricted?	Yes	Remove obstruction, then go to Step 18.
3		No	Inspect if there are any obstruction in the A/C unit passage, then go to Step 18.
4*	INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER RELAY SYSTEM OR ELSEWHERE Turn the airflow volume control switch on. Measure the voltage at the following terminal (wiring harness side). Blower fan controller terminal F (blower motor operation signal) Is voltage B+?	Yes	Go to Step 8.
4*		No	Go to the next step.
5*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN FUSE BLOCK AND BLOWER RELAY) OR ELSEWHERE Measure the voltage at the following terminals (wiring harness side). Blower relay terminal A (B+ signal) Blower relay terminal B (B+ signal) Is the voltage B+?	Yes	Go to the next step.
5*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower relay terminal and HEATER 40 A fuse. 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 18.
6*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER RELAY AND GROUND) OR ELSEWHERE Measure the voltage at the following terminal (wiring harness side). Blower relay terminal D (ground) Is the voltage approx. 0 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 blower relay terminal and front body control module (FBCM) 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 18.
7*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER RELAY AND BLOWER FAN CONTROLLER) OR BLOWER RELAY Measure the voltage at the following terminal (wiring harness side). Blower relay terminal C (blower motor operation signal) Is the voltage B+?	Yes	Repair the wiring harness for lack of continuity between the blower relay and blower fan controller, then go to Step 18.
7*		No	Replace the blower relay, then go to Step 18. (See RELAY LOCATION .)
8	INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER MOTOR 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] .) Inspect the blower motor. (See BLOWER MOTOR INSPECTION .) Is the blower motor normal?	Yes	Go to the next step.
8		No	Replace the blower motor, then go to Step 18. (See BLOWER MOTOR REMOVAL/INSTALLATION .)
9*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER FAN CONTROLLER AND CLIMATE CONTROL UNIT) OR ELSEWHERE Disconnect the blower fan controller connector. (See BLOWER FAN CONTROLLER REMOVAL/INSTALLATION .) 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: Bower fan controller terminal B- climate control unit terminal 1E With single type climate control unit: Bower fan controller terminal B- climate control unit terminal Q Is there continuity?	Yes	Go to the next step.
9*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller 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 18.
10*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO GROUND BETWEEN BLOWER FAN CONTROLLER AND CLIMATE CONTROL UNIT) OR ELSEWHERE Inspect for continuity between the following terminal (wiring harness-side) and body ground. Blower fan controller terminal B Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller 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 18.
10*		No	Go to the next step.
11*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO POWER SUPPLY BETWEEN BLOWER FAN CONTROLLER AND CLIMATE CONTROL UNIT) OR ELSEWHERE 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 the voltage at the following terminal (wiring harness side). Blower fan controller terminal B Is the voltage approx. 0 V?	Yes	Go to the next step.
11*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller 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 18.
12*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO POWER SUPPLY BETWEEN BLOWER FAN CONTROLLER AND BODY GROUND) OR ELSEWHERE Measure the voltage at the following terminal (wiring harness side). Blower fan controller terminal C Is the voltage approx. 0 V?	Yes	Go to the next step.
12*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller terminal and body ground. 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 18.
13*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER FAN CONTROLLER AND BODY GROUND) 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] .) Inspect for continuity between the following terminal (wiring harness-side) and body ground. Blower fan controller terminal C 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 blower fan controller terminal and body ground. 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 18.
14*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER FAN CONTROLLER AND BLOWER MOTOR) OR ELSEWHERE Inspect for continuity between the following terminals (wiring harness-side). Bower fan controller terminal E- blower motor terminal B Bower fan controller terminal A- blower motor terminal A Is there continuity?	Yes	Go to the next step.
14*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller terminal and blower motor. 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 18.
15*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO GROUND BETWEEN BLOWER FAN CONTROLLER AND BLOWER MOTOR) OR ELSEWHERE Inspect for continuity between the following terminal (wiring harness-side) and body ground. Bower fan controller terminal E Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller terminal and blower motor 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 18.
15*		No	Go to the next step.
16*	INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO POWER SUPPLY BETWEEN BLOWER FAN CONTROLLER AND BLOWER MOTOR) OR ELSEWHERE 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 the voltage at the following terminal (wiring harness side). Bower fan controller terminal E Bower fan controller terminal A Is the voltage approx. 0 V?	Yes	Go to the next step.
16*		No	Refer to the wiring diagram and verify whether or not there is a common connector between blower fan controller terminal and blower motor. 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 18.
17	INSPECT BLOWER UNIT 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 fan in blower unit. (See BLOWER UNIT DISASSEMBLY/ASSEMBLY .) Is the fan free of interference with the blower unit case? Is the fan free of foreign matter and obstructions? Is the fan normal?	Yes	Replace the blower fan controller, then go to the next step. (See BLOWER FAN CONTROLLER REMOVAL/INSTALLATION .)
17		No	Remove obstruction, repair or replace the fan and blower unit case, then go to the next step.
18	VERIFY THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR Is air discharged from vent?	Yes	Troubleshooting completed. Explain repairs to customer.
18		No	Recheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs. If the malfunction recurs, replace the climate control unit. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .)