Home/Mazda/3/Mazda 3 BL (2008-2011)/Repair manual/Automatic HVAC System/Symptom Troubleshooting (HVAC): Diagnosis
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Symptom Troubleshooting (HVAC): Diagnosis Mazda 3 BL

TROUBLESHOOTING INDEX

No.TROUBLESHOOTING ITEMDESCRIPTION
1Insufficient air (or no air) blown from ventsProblem with each vent or duct or both. Airflow mode does not change.
2Amount of air blown from vents does not change. (Full-auto air conditioner)Malfunction in blower system
3Amount of air blown from vents does not change. (Manual air conditioner)Malfunction in blower system
4Air intake mode does not change.Air intake mode does not change when switching REC/FRESH mode.
5No temperature control with climate control unitMalfunction in A/C unit and/or climate control unit air mix system or both
6Windshield fogged.A/C compressor does not operate while airflow mode is in DEFROSTER or HEAT/DEF modes. Air intake mode does not change to FRESH while airflow mode is in DEFROSTER or HEAT/DEF modes.
7Air from vents not cold enoughMagnetic clutch operates but A/C system malfunctions.
8No cool airMagnetic clutch does not operate.
9Noise while operating A/C systemNoise from magnetic clutch, A/C compressor, hose or refrigerant line

TROUBLESHOOTING INDEX

Diagnostic procedure

STEPINSPECTIONACTION
1INSPECT AIRFLOW MODE ACTUATOR Inspect airflow mode actuator. Is it normal?YesGo to the next step.
NoRepair or replace malfunctioning part in accordance with further inspection result.
2INSPECT TO SEE WHETHER MALFUNCTION IS IN VENT MODE OR OTHER MODES Dose air blow out when in VENT mode?YesGo to Step 5.
NoGo to the next step.
3INSPECT VENT Is vent clogged?YesRemove obstruction, then go to Step 9.
NoGo to the next step.
4VERIFY THAT DUCT IN DASHBOARD IS INSTALLED Is duct in dashboard properly installed?YesInspect the duct for clogging, deformation and air leakage, then go to Step 9.
NoInstall the duct securely in the proper position, then go to Step 9.
5INSPECT TO SEE WHETHER MALFUNCTION IS IN HEAT MODE OR DEFROSTER MODE Does air blow out when in the HEAT mode?YesGo to the next step.
NoInspect the vent for clogging, then go to Step 9.
6INSPECT DEFROSTER MODE Does air blow out when in the DEFROSTER mode?YesOperation is normal. Recheck malfunction symptoms.
NoGo to the next step.
7INSPECT VENT Is vent clogged?YesRemove obstruction, then go to Step 9.
NoGo to the next step.
8VERIFY THAT DEFROSTER DUCT IS INSTALLED Is the defroster duct properly installed?YesInspect the duct for clogging, deformity, and air leakage, then go to the next step.
NoInstall the duct securely in proper position, then go to the next step.
9CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT RECUR AFTER REPAIR Does air blow out?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT HEATER 40 A FUSE Inspect the HEATER 40 A fuse. Is it normal?YesGo to the next step.
NoReplace the fuse, then go to Step 15. If the fuse burns out immediately, go to the next step.
2INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT OR ELSEWHERE Turn the ignition switch to the ON position. Recirculate air inside the vehicle. Does the blower motor rotate smoothly?YesGo to Step 4.
NoGo to the next step.
3INSPECT A/C UNIT INTAKE VENT Is A/C unit intake vent clogged?YesRemove obstruction, then go to Step 15.
NoInspect if there are any obstruction in the A/C unit passage, then go to Step 15.
4*INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER RELAY SYSTEM OR POWER MOS FET SYSTEM Turn the ignition switch to ON position. Measure the voltage at the following blower motor terminal. Terminal B (blower motor operation signal) Is voltage approx. 12 V?YesGo to Step 8.
NoGo 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 blower relay terminals. Terminal B (IG2 signal) Terminal A (B+ signal) Is the voltage approx. 12 V?YesGo to the next step.
NoRepair the wiring harness between the blower relay and HEATER 40 A fuse, then go to Step 15.
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 blower relay terminal. Terminal D (GND signal) Is the voltage approx. 0 V?YesGo to the next step.
NoRepair the wiring harness between the blower relay and ground, then go to Step 15.
7*INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER RELAY AND BLOWER MOTOR) OR BLOWER RELAY Measure the voltage at the following blower relay terminal. Terminal E (blower motor operation signal) Is the voltage approx. 12 V?YesRepair the wiring harness between the blower relay and blower motor, then go to Step 15.
NoReplace the blower relay, then go to Step 15.
8*INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER MOTOR OR ELSEWHERE Measure the voltage at the following blower motor terminal. Terminal B (blower motor operation signal) Is the voltage approx. 12 V?YesGo to the next step.
NoInspect the blower motor, then go to Step 15.
9*INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER MOTOR AND POWER MOS FET) OR ELSEWHERE Measure the voltage at the following terminal of power MOS FET. Terminal B (blower motor operation signal) Is voltage approx. 12 V?YesGo to the next step.
NoRepair the wiring harness between the blower motor and power MOS FET, then go to Step 15.
10*INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER MOS FET AND GROUND) OR ELSEWHERE Measure the voltage at the following power MOS FET terminal. Terminal A (blower motor operation signal) Is the voltage approx. 0 V?YesGo to the next step.
NoRepair the wiring harness between the power MOS FET and ground, then go to Step 15.
11INSPECT A/C UNIT Inspect the fan in A/C unit. Is the fan free of interference with the A/C unit case? Is the fan free of foreign material and obstruction? Is the fan normal?YesGo to the next step.
NoRemove obstruction, repair or replace the fan and A/C unit case, then go to Step 15.
12*INSPECT TO SEE WHETHER MALFUNCTION IS IN POWER MOS FET OR ELSEWHERE Disconnect power MOS FET connector. Measure the voltage at the following power MOS FET terminal. Terminal B (blower motor control signal) Is voltage approx. 10 V?YesReplace the power MOS FET, then go to Step 15.
NoGo to the next step.
13*INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER MOS FET AND CLIMATE CONTROL UNIT) OR ELSEWHERE Turn the ignition switch to the LOCK position. Disconnect climate control unit connector. Inspect for continuity at the following terminals between the power MOS FET and climate control unit. Terminal B--F (blower motor control signal) Terminal C--D (blower motor feedback signal) Is there continuity?YesGo to the next step.
NoRepair the wiring harness between the power MOS FET and climate control unit, then go to Step 15.
14*INSPECT TO SEE WHETHER MALFUNCTION IS IN CLIMATE CONTROL UNIT OR WIRING HARNESS (SHORT TO GROUND IN WIRING HARNESS BETWEEN POWER MOS FET AND CLIMATE CONTROL UNIT) Inspect for continuity at the following terminal between the power MOS FET and ground. Terminal B (blower motor control signal)-- ground Is there continuity?YesRepair the wiring harness between the power MOS FET and ground, then go to the next step.
NoReplace the climate control unit, then go to the next step.
15CONFIRM THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR Is air discharged from vent?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT BLOWER SYSTEM Inspect the following systems and electrical parts. Blower relay (See RELAY INSPECTION .) Blower motor (See BLOWER MOTOR INSPECTION .) Resistor (See RESISTOR INSPECTION .) Fan switch (See FAN SWITCH INSPECTION .) Related wiring harnesses Are they normal?YesGo to the next step.
NoRepair or replace the malfunctioning part, then go to Step 5.
2INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT OR ELSEWHERE Turn the ignition switch to the ON position. Turn the fan switch on. Recirculate air inside the vehicle. Does the blower fan rotate smoothly?YesGo to Step 4.
NoGo to the next step.
3INSPECT A/C UNIT Inspect blower fan. Is the fan free of interference from the A/C unit case? Is the fan free of foreign material and obstructions? Is the fan normal?YesGo to the next step.
NoRemove obstruction, repair or replace the fan and A/C unit case, then go to Step 5.
4INSPECT A/C UNIT INTAKE VENT Is the A/C unit intake vent clogged?YesRemove obstruction, then go to the next step.
NoInspect if there are any obstructions in the A/C unit passage, then go to the next step.
5VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR Does air blow out?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1*INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN AIR INTAKE ACTUATOR, WIRING HARNESS (BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR) OR ELSEWHERE Turn the ignition switch to the ON position. Measure the voltages at the following climate control unit terminals. Terminal O (24-pin, FRESH motor drive signal) Terminal Q (24-pin, RECIRCULATE motor drive signal) (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Are voltages normal?YesGo to the next step.
NoGo to Step 3.
2*INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN AIR INTAKE ACTUATOR OR WIRING HARNESS (BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR) Measure the voltages at the following air intake actuator terminals. (See AIR INTAKE ACTUATOR INSPECTION .) Terminal E (FRESH motor drive signal) Terminal C (RECIRCULATE motor drive signal) Are voltages as shown below? (See AIR INTAKE ACTUATOR INSPECTION .) Terminal E: approx, 0.5 V during RECIRCULATE and approx. 10 V during FRESH Terminal C: approx. 10 V during RECIRCULATE and approx. 0.5 V during FRESHYesReplace the air intake actuator, then go to Step 8.
NoRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 8.
3INSPECT TO SEE WHETHER MALFUNCTION IS IN AIR INTAKE ACTUATOR OR ELSEWHERE Disconnect the air intake actuator connector. Measure the voltages at the following climate control unit terminals. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Terminal O (FRESH motor drive signal) Terminal Q (RECIRCULATE motor drive signal) Are voltages normal?YesInspect the air intake actuator, then go to Step 8.
NoGo to the next step.
4INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO B+ BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR) OR ELSEWHERE Disconnect the climate control unit connector. Measure the voltages at the following climate control unit terminals. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Terminal O (FRESH motor drive signal) Terminal Q (RECIRCULATE motor drive signal) Are voltages approx. 0 V?YesGo to the next step.
NoRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 8.
5INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO GROUND BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR) OR ELSEWHERE Turn the ignition switch to the LOCK position. Inspect for continuity at the following terminals between the climate control unit and ground. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Terminal O (FRESH motor drive signal) Terminal Q (RECIRCULATE motor drive signal) Is there continuity?YesRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 8.
NoGo to the next step.
6INSPECT AIR INTAKE LINK Inspect the air intake links. Is there grease on link? Are the links securely and properly installed? Are the links free of obstructions and hindrances? Are the above items normal?YesGo to the next step.
NoApply grease to the links. If any the links are damaged, replace the air intake actuator, then go to Step 8.
7INSPECT TO SEE WHETHER MALFUNCTION IS IN CLIMATE CONTROL UNIT OR AIR INTAKE DOOR Inspect the A/C unit air intake door. Is the door free of obstructions, cracks, and damage? Are the doors securely and properly installed? Are the above items normal?YesReplace the climate control unit, then go to the next step. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSTALLATION [MANUAL AIR CONDITIONER] .)
NoRemove obstruction, or install the doors in the proper position. If any doors are cracked or damaged, replace them, then go to the next step.
8CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT RECUR AFTER REPAIR Does the air intake mode change smoothly?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT COOLANT TEMPERATURE Is the coolant sufficiently warmed up?YesGo to the next step.
NoWarm up the engine, then go to Step 8.
2INSPECT A/C UNIT AIR MIX SYSTEM Inspect the A/C unit air mix links, air mix cranks, air mix rods, air mix actuator, and wire clamp. Is there grease on links and cranks? Are links, cranks, and rods securely installed in their proper positions? Is wire clamp free of deformation? Are the above items normal?YesGo to the next step.
NoApply grease or install the links, cranks, and rods securely in their proper positions, repair or replace the air mix actuator or wire clamp, then go to Step 8.
3VERIFY THAT AIR MIX WIRE FROM A/C UNIT IS POSITIONED SECURELY AND CORRECTLY (IF AVAILABLE) Is the air mix wire securely installed in the correct position in relation to the A/C unit air mix links?YesGo to the next step.
NoAdjust the air mix wire or install securely in the correct position, then go to Step 8.
4INSPECT CLIMATE CONTROL UNIT Inspect the climate control unit, (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Is the climate control unit normal?YesGo to the next step.
NoRepair or replace the climate control unit, then go to Step 8. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSTALLATION [MANUAL AIR CONDITIONER] .)
5INSPECT A/C UNIT Is there any foreign material or obstruction in the A/C unit air mix doors?YesRemove obstruction, then go to Step 8.
NoGo to the next step.
6INSPECT A/C UNIT AIR MIX DOOR Is the A/C unit air mix door securely and properly installed?YesInspect the air mix door for cracks or damage, then go to the next step.
NoInstall the air mix door securely in the proper position, then go to the next step.
7INSPECT HEATER LINE Inspect the heater lines. Is the heater piping free of damage and cracks? Are the heater piping connections free of engine coolant leakage? Are the heater piping connections securely tightened? Are the heater piping installation points on A/C unit free of engine coolant leakage? Are the above items normal?YesOperation is normal. Recheck malfunction symptoms.
NoIf heater piping connections are loose, tighten the connections to the specified torque. Repair or replace the heater piping, then go to the next step.
8VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR Does the unit operate in every temperature setting?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1COOL AIR BLOW OUT INSPECTION When both the A/C and fan switch in the climate control unit are on, does cool air blow out from the front vent?YesGo to the next step.
NoGo to Step 1 of troubleshooting index No.7.
2INSPECT CLIMATE CONTROL UNIT POWER SUPPLY FUSE FOR B+ SIGNAL Is the climate control unit power supply fuse for B+ signal normal?YesGo to the next step.
NoInspect for a short to ground on blown fuse circuit. Repair or replace if necessary. Install appropriate amperage fuse.
3INSPECT AIR INTAKE ACTUATOR Inspect the air intake actuator. Is there grease on the link? Is the link securely and properly positioned? Is the link free of obstructions? Are the above items normal?YesGo to the next step.
NoApply grease or install the link properly and securely, remove obstruction, then go to Step 14.
*4INSPECT WIRING HARNESS BETWEEN FUSE BLOCK AND CLIMATE CONTROL UNIT FOR CONTINUITY Disconnect the climate control unit connector (24-pin). Turn the ignition switch to the ON position. Measure the voltage at climate control unit terminal J (B+ signal). (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Is the voltage approx. 12 V?YesGo to the next step.
NoRepair the wiring harness between the fuse block and climate control unit, then go to Step 14.
*5INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND GROUND FOR VOLTAGE Measure the voltage at climate control unit terminal V (Ground). (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Is the voltage approx. 0V?YesGo to the next step.
NoRepair the wiring harness between the climate control unit and ground, then go to Step 14.
6VERIFY WHETHER MALFUNCTION IS IN A/C UNIT AIR INTAKE DOOR OR ELSEWHERE Turn the ignition switch to the LOCK position. Connect the climate control unit connector (24-pin). Remove the air intake actuator. Turn the ignition switch to the ON position. Set the fan switch to 4th position. Does the air intake mode (RECIRCULATE, FRESH) change smoothly when the air intake link is operated by hand?YesGo to the next step.
NoGo to Step 12.
7INSPECT AIR INTAKE ACTUATOR Inspect the air intake actuator. (See AIR INTAKE ACTUATOR INSPECTION .) Is it normal?YesGo to the next step.
NoReplace the air intake actuator, go to Step 14.
8INSPECT AIR INTAKE SELECTOR SWITCH AND DEFROSTER SWITCH IN CLIMATE CONTROL UNIT Measure the voltage at climate control unit connector (24-pin) terminals O and Q. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Is it normal?YesGo to the next step.
NoReplace the climate control unit, then go to Step 14. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSTALLATION [MANUAL AIR CONDITIONER] .)
*9INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR FOR CONTINUITY Turn the ignition switch to the LOCK position. Is there continuity between the following climate control unit terminals and air intake actuator terminals? (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) (See AIR INTAKE ACTUATOR INSPECTION .) Terminal E --Terminal O (FRESH signal) Terminal C --Terminal Q (RECIRCULATE signal)YesGo to the next step.
NoRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 14.
*10INSPECT 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? (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Terminal O (FRESH signal) Terminal Q (RECIRCULATE signal)YesRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 14.
NoGo to the next step.
*11INSPECT WIRING HARNESS BETWEEN CLIMATE CONTROL UNIT AND AIR INTAKE ACTUATOR FOR SHORT TO B+ Turn the ignition switch to the ON position. Measure the voltage at the following climate control unit terminals. (See CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER] .) Terminal O (FRESH signal) Terminal Q (RECIRCULATE signal) Is the voltage approx. 12 V?YesRepair the wiring harness between the climate control unit and air intake actuator, then go to Step 14.
NoReplace the climate control unit, then go to Step 14. (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER] .) (See CLIMATE CONTROL UNIT INSTALLATION [MANUAL AIR CONDITIONER] .)
12INSPECT A/C UNIT AIR INTAKE DOOR Is there any foreign material or obstruction in the A/C unit air intake door?YesRemove obstruction, then go to Step 14.
NoGo to the next step.
13VERIFY THAT A/C UNIT AIR INTAKE DOOR IS POSITIONED SECURELY AND PROPERLY Is the A/C unit air intake door securely and properly positioned?YesInspect the air intake door for cracks or damage, then go to the next step.
NoInstall the air intake door securely in the proper position, then go to the next step.
14VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR Does the malfunction disappear?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT DRIVE BELT Inspect the drive belt. (See DRIVE BELT INSPECTION [LF, L3] .) Is it normal?YesGo to the next step.
NoAdjust or replace the drive belt, then go to Step 20.
2INSPECT REFRIGERANT SYSTEM PERFORMANCE Perform refrigerant system performance test. (See REFRIGERANT SYSTEM PERFORMANCE TEST .) Is the operation normal?YesOperation is normal. (Recheck malfunction symptoms.)
NoGo to the next step.
3INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT INTAKE AND CONDENSER OR ELSEWHERE Are the refrigerant high-pressure and low-pressure values both high?YesGo to the next step.
NoGo to Step 6.
4INSPECT A/C UNIT INTAKE Is the A/C unit intake clogged?YesRemove obstruction, then go to Step 20. (If air does not reach the evaporator in the A/C unit, heat exchange does not occur and refrigerant pressure becomes high. Therefore, removal of obstruction is necessary.)
NoGo to the next step.
5INSPECT CONDENSER Inspect the condenser. (See CONDENSER INSPECTION .) Is it normal?YesAdjust refrigerant to the specified amount, then go to Step 20. (Excessive amount of refrigerant.)
NoReplace the condenser, or repair and clean the condenser fins, then go to Step 20.
6INSPECT TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE, RECEIVER/DRIER AND REFRIGERANT LINES OR ELSEWHERE Are the refrigerant high-pressure and low-pressure values low?YesGo to the next step.
NoGo to Step 14.
7INSPECT TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE AND RECEIVER/DRIER OR ELSEWHERE Immediately after the A/C compressor operates, does the refrigerant high-pressure value momentarily rise to correct value, then fall and stay below it? (Is there negative pressure on low-pressure side?)YesGo to the next step.
NoGo to Step 10.
8INSPECT TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE OR RECEIVER/DRIER Turn the A/C switch off and let the air conditioner stop for 10 min. Start the engine. Turn the both A/C switch and fan switch on. Does the malfunction occur after the A/C compressor turns on?YesGo to the next step.
NoReplace the condenser and bleed refrigerant line for 30 min or more using a vacuum pump, add refrigerant to the specified level, then go to Step 20. (Since water has intermixed in the receiver/drier and it is saturated, replacement is necessary.)
9VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN A/C UNIT IS POSITIONED SECURELY AND CORRECTLY Is the expansion valve heat-sensing tube in the A/C unit securely installed in the proper position?YesReplace the expansion valve, then go to Step 20. (Since the valve closes too much, replacement is necessary.)
NoInstall the heat-sensing tube securely in the proper position, then go to Step 20.
10INSPECT REFRIGERANT LINE Inspect the refrigerant lines. Is the piping free of damage and cracks? Are the piping connections free of oil grime? (Visual inspection) Are the piping connections free of gas leakage? Are the piping installation points on the condenser free of gas leakage? Are the piping installation points on the receiver/drier free of gas leakage? Are the piping installation points on the A/C compressor free of gas leakage? Are the piping installation points on the A/C unit free of gas leakage? Perform gas leakage inspection using a gas leak tester. Are the above items normal?YesGo to the next step.
NoIf the piping or A/C component (s) are damaged or cracked, replace them. Then go to Step 20. If there is no damage, go to Step 13.
11INSPECT EVAPORATOR PIPING CONNECTION IN A/C UNIT FOR GAS LEAKAGE Are piping the connections for the evaporator in the A/C unit free of gas leakage?YesIf the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard. Adjust refrigerant to the specified amount, then go to Step 20.
NoIf the piping is damaged or cracked, replace it. Then go to Step 20. If there is no damage, go to the next step.
12INSPECT EVAPORATOR PIPING CONNECTION IN A/C UNIT FOR LOOSE Are the piping connections for the evaporator in the A/C unit loose?YesTighten the connections to the specified torque, adjust both compressor oil and refrigerant to the specified amount, then go to Step 20.
NoIf the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard. Replace the O-ring on piping, adjust refrigerant to the specified amount, then go to Step 20.
13INSPECT PIPING CONNECTION FOR LOOSE Are the piping connections loose?YesTighten the connections to the specified torque, adjust both compressor oil and refrigerant to the specified amount, then go to Step 20.
NoIf the vane makes a noise, add 10 ml {10 cc, 0.34 fl oz} of compressor oil to the A/C compressor. Verify that the noise is no longer heard. Replace O-ring on piping, adjust refrigerant to specified amount, then go to Step 20.
14INSPECT TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE, AIR MIX ACTUATOR AND COMPRESSOR OIL OR ELSEWHERE Does the refrigerant high-pressure value hardly increase?YesGo to the next step. (Pressure hardly increases.)
NoGo to Step 17.
15INSPECT TO SEE WHETHER MALFUNCTION IS IN COMPRESSOR OIL AMOUNT AND A/C COMPRESSOR OR ELSEWHERE When the engine is racing, does the high-pressure value increase?YesReturn to Step 3.
NoGo to the next step.
16INSPECT TO SEE WHETHER MALFUNCTION IS IN COMPRESSOR OIL AMOUNT OR A/C COMPRESSOR After compressor oil is replenished each 10 ml {10 cc, 0.34 fl oz} , does high-pressure value increase?YesTroubleshooting completed. (Explain to customer that cause was insufficient compressor oil.)
NoReplace the A/C compressor, then go to Step 20. (Cause is defective A/C compressor.)
17INSPECT TO SEE WHETHER MALFUNCTION IS IN EXPANSION VALVE OR ELSEWHERE Is only refrigerant low-pressure value high?YesGo to Step 19.
NoGo to the next step.
18VERIFY THAT AIR MIX IS INSTALLED SECURELY AND PROPERLY Are the A/C unit air mix links, air mix cranks, and air mix rods securely and properly installed?YesSet the fan switch to 4th position. Turn the A/C switch on. Set FRESH mode. Set temperature control to MAX COLD. Set VENT mode. Start and run the engine at 1,500 rpm for 10 min. Run the engine at idle for 1 min. Within 12 s , idle --> 4,000 rpm --> idle. Perform cycle 5 times. Run the engine at idle for 30 s. Drain the compressor oil completely from the A/C compressor and verify the amount. If there is approx. 90 ml {90 cc, 3.0 fl oz} of compressor oil, go to Step 20. If there is more than 90 ml {90 cc, 3.0 fl oz} of compressor oil, remove surplus oil and fill the A/C compressor with 90 ml {90 cc, 3.0 fl oz} of compressor oil. Repeat Steps (1) to (5). (Cause is excessive amount of compressor oil.)
NoRepair or install the links, cranks and rods securely in the proper position, then go to Step 20.
19VERIFY THAT EXPANSION VALVE HEAT-SENSING TUBE WITHIN A/C UNIT IS POSITIONED SECURELY AND CORRECTLY Is the expansion valve heat-sensing tube in the A/C unit securely installed in the proper position?YesReplace the expansion valve, then go to the next step. (Since the valve opens too much, replacement is necessary.)
NoInstall the heat-sensing tube securely in the proper position, then go to the next step.
20VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR Does cool air blow out? (Are results of refrigerant system performance test normal?)YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT AIR BLOW OUT Does air blow out?YesGo to the next step.
NoGo to Step 1 of troubleshooting indexes No.1 and 2.
2INSPECT FUSE Are the A/C relay power supply fuses normal?YesGo to the next step.
NoReplace the fuse, then go to Step 5. If fuse burns out immediately, go to the next step.
3INSPECT A/C COMPRESSOR OPERATION Start the engine. Turn the A/C switch and fan switch on. Does the A/C compressor operate?YesGo to Step 1 of troubleshooting index No.7.
NoGo to Step 1 of troubleshooting index No.23. (See NO.23 A/C DOES NOT WORK SUFFICIENTLY [LF, L3] .)
4INSPECT EVAPORATOR TEMPERATURE SENSOR Inspect the evaporator temperature sensor. Is it normal?YesGo to the next step.
NoReplace the evaporator temperature sensor, then go to the next step.
5CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT RECUR AFTER REPAIR Does cool air blow out? (Are the results of refrigerant system performance test normal?)YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.

DIAGNOSIS PROCEDURE

STEPINSPECTIONACTION
1INSPECT A/C COMPRESSOR SLIPPAGE NOISE Is there a squeaking or whirling sound (A/C compressor slippage noise)?YesGo to Step 12.
NoGo to the next step.
2INSPECT A/C COMPRESSOR INTERFERENCE NOISE Is there a rattling or vibrating sound (interference noise)?YesGo to Step 16.
NoGo to the next step.
3INSPECT MAGNETIC CLUTCH OPERATION NOISE Is there a clicking sound (magnetic clutch operation noise)?YesAdjust the clearance between the pressure plate of magnetic clutch and A/C compressor pulley, then go to Step 17. (See MAGNETIC CLUTCH ADJUSTMENT .)
NoCondition is normal. (Recheck malfunction symptoms.) Go to the next step.
4INSPECT IDLE SPEED Inspect idle speed. (See ENGINE TUNE-UP [LF, L3] .) Is it normal?YesGo to the next step.
NoFollow the repair instruction described in SYMPTOM TROUBLESHOOTING (LF, L3), then go to Step 17.
5INSPECT REFRIGERANT AMOUNT Inspect refrigerant amount. Is it normal?YesGo to Step 8.
NoGo to the next step.
6INSPECT REFRIGERANT LINES Inspect the refrigerant lines. Is the piping free of damage and cracks? Are the piping connections free of oil grime? (Visual inspection) Are piping connections free of gas leakage? Are the piping installation points on the condenser free of gas leakage? Are the piping installation points on the receiver/drier free of gas leakage? Are the piping installation points on the A/C compressor free of gas leakage? Are the piping installation points on the A/C unit free of gas leakage Perform gas leakage inspection using a gas leak tester. Are the above items normal?YesGo to the next step.
NoIf the piping or A/C component (s) is damaged or cracked, replace them, then go to Step 17. If there is gas leakage, repair or replace connection and replace the condenser (1) , then go to Step 17.
7INSPECT EVAPORATOR PIPING CONNECTIONS IN A/C UNIT FOR GAS LEAKAGE Are the piping connections for the evaporator in the A/C unit free of gas leakage?YesAdjust refrigerant amount to the specified level, then go to Step 17.
NoIf the piping is damaged or cracked, replace it them, then go to Step 17. If there is gas leakage, repair or replace the connecting parts and replace the condenser (1) , then go to Step 17.
8INSPECT TO SEE WHETHER MALFUNCTION IS IN COMPRESSOR OIL OR ELSEWHERE Add 20 ml {20 cc, 0.8 fl oz} of compressor oil. Is noise heard when racing the engine?YesGo to the next step.
NoTroubleshooting completed. Explain repair to customer.
9INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR ELSEWHERE Drain compressor oil. Is it contaminated with metal particles?YesGo to the next step.
NoReplace the A/C compressor, then go to Step 17.
10INSPECT TO SEE WHETHER MALFUNCTION IS SOMEWHERE IN A/C SYSTEM OR ELSEWHERE Is compressor oil whitish and mixed with water?YesReplace entire A/C system (excluding heater), then go to Step 17.
NoGo to the next step.
11INSPECT A/C COMPRESSOR OIL Is compressor oil darker than normal and contaminated with aluminum chips?YesReplace the A/C compressor and condenser, then go to Step 17. (Since the A/C compressor may be worn and receiver/drier may be clogged, replacement of the receiver/drier is necessary.)
NoCondition is normal. Recheck malfunction symptoms.
12INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR ELSEWHERE Is noise heard immediately after the A/C compressor is stopped?YesReplace the A/C compressor, then go to Step 17. (A/C compressor discharge valve left open)
NoGo to the next step.
13INSPECT DRIVE BELT Inspect drive belt. (See DRIVE BELT INSPECTION [LF, L3] .) Is it normal?YesGo to the next step.
NoAdjust or replace drive belt, then go to Step 17.
14INSPECT DRIVE BELT CONDITION Is the drive belt worn? Does it have foreign material imbedded in it, or have oil on it?YesRemove obstruction, remove oil, or replace the drive belt, then go to Step 17.
NoGo to the next step.
15INSPECT MAGNETIC CLUTCH Inspect the magnetic clutch. (See MAGNETIC CLUTCH INSPECTION [LF, L3] .) Is it normal?YesReplace the A/C compressor (excluding the pressure plate, A/C compressor pulley, and stator), then go to Step 17.
NoReplace the magnetic clutch, then go to Step 17.
16INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR REFRIGERANT LINE Is noise emitted from the A/C compressor?YesVisually inspect the A/C compressor, replace appropriate parts if necessary, then go to the next step.
NoIf noise is due to refrigerant lines, repair detached or missing clips, tighten loose bolts, then go to the next step.
17VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR Has A/C compressor noise stopped?YesTroubleshooting completed. Explain repairs to customer.
NoRecheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.
(1) If there is gas leakage, air enters into the A/C system. The desiccant within the receiver/drier absorbs the moisture from the air and becomes saturated. If the A/C system is used in this condition, the inside of the A/C compressor will begin to rust due to this moisture, which may cause lock up or noise to occur. Therefore, replacement of the receiver/drier is necessary.
(1)If there is gas leakage, air enters into the A/C system. The desiccant within the receiver/drier absorbs the moisture from the air and becomes saturated. If the A/C system is used in this condition, the inside of the A/C compressor will begin to rust due to this moisture, which may cause lock up or noise to occur. Therefore, replacement of the receiver/drier is necessary.

DIAGNOSIS PROCEDURE