NO.10 NOISE WHILE OPERATING A/C SYSTEM.

id070300801400

10 | Noise while operating A/C system.
DESCRIPTION | • Problem with A/C basic system installation • Noise from magnetic clutch, A/C compressor, hose or refrigerant line.
POSSIBLE CAUSE | • Magnetic clutch operation noise • A/C compressor vane noise • A/C compressor slippage noise • Hose or refrigerant line interference noise

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | CHECK A/C COMPRESSOR VANE NOISE • Is there a jingling, popping, beeping, or buzzing sound (A/C compressor vane noise)? | Yes | Go to Step 5.
No | Go to the next step.
2 | INSPECT A/C COMPRESSOR SLIPPAGE NOISE • Is there a squeaking or whirling sound (A/C compressor slippage noise)? | Yes | Go to Step 14.
No | Go to the next step.
3 | INSPECT A/C COMPRESSOR INTERFERENCE NOISE • Is there a rattling or vibrating sound (interference noise)? | Yes | Go to Step 18.
No | Go to the next step.
4 | INSPECT MAGNETIC CLUTCH OPERATION NOISE • Is there a clicking sound (magnetic clutch operation noise)? | Yes | Adjust clearance between pressure plate of magnetic clutch and A/C compressor pulley, then go to Step 19. (See MAGNETIC CLUTCH CLEARANCE INSPECTION.)
No | Condition is normal. (Recheck malfunction symptoms.)
5 | INSPECT A/C COMPRESSOR NOISE TIME • Is noise heard continuously for more than 3 s after A/C compressor comes on? | Yes | Go to the next step.
No | Condition is normal. (Noise occurs for 2—3 s immediately after A/C compressor turns on.)
6 | INSPECT IDLE SPEED • Inspect idle speed. (See ENGINE TUNE-UP [MZI-3.7].) • Is it okay? | Yes | Go to the next step.
No | Follow the repair instruction described in section 01, then go to Step 19.
7 | INSPECT REFRIGERANT AMOUNT • Inspect refrigerant amount. • Is it okay? | Yes | Go to Step 10.
No | Go to the next step.
8 | INSPECT REFRIGERANT LINES • Inspect refrigerant lines. ― Is piping free of damage and cracks? ― Are piping connections free of oil grime? (Visual inspection) ― Are piping connections free of gas leakage? ― Are piping installation points on condenser free of gas leakage? ― Are piping installation points on receiver/drier free of gas leakage? ― Are piping installation points on A/C compressor free of gas leakage? ― Are piping installation points on A/C unit free of gas leakage ― Perform gas leak inspection using gas leak tester. • Are above items okay? | Yes | Go to the next step.
No | If piping or A/C component(s) is damaged or cracked, replace then go to Step 19. If there is gas leakage, repair or replace connection and replace condenser*, then go to Step 19.
9 | INSPECT EVAPORATOR PIPING CONNECTIONS IN A/C UNIT FOR GAS LEAKAGE • Are piping connections for evaporator in A/C unit free of gas leakage? | Yes | Adjust refrigerant amount to specified level, then go to Step 19.
No | If piping is damaged or cracked, replace then go to Step 19. If there is gas leakage, repair or replace connection and replace condenser*, then go to Step 19.
10 | CHECK TO SEE WHETHER MALFUNCTION IS IN COMPRESSOR OIL OR ELSEWHERE • Add 20 ml {20 cc, 0.68 fl oz} of compressor oil. • Is noise heard when racing engine? | Yes | Go to the next step.
No | Troubleshooting completed. Explain repair to customer.
11 | CHECK TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR ELSEWHERE • Drain compressor oil. • Is it contaminated with metal particles? | Yes | Go to the next step.
No | Replace A/C compressor, then go to Step 19.
12 | CHECK TO SEE WHETHER MALFUNCTION IS SOMEWHERE IN A/C SYSTEM OR ELSEWHERE • Is compressor oil whitish and mixed with water? | Yes | Replace entire A/C system (excluding heater), then go to Step 19.
No | Go to the next step.
13 | INSPECT A/C COMPRESSOR OIL • Is compressor oil darker than normal and contaminated with aluminum chips? | Yes | Replace A/C compressor and condenser, then go to Step 19. (Since A/C compressor may be worn and receiver/drier may be clogged, replacement of receiver/drier is necessary.)
No | Condition is normal. Recheck malfunction symptoms.
14 | CHECK TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR ELSEWHERE • Is noise heard immediately after A/C compressor is stopped? | Yes | Replace A/C compressor, then go to Step 19. (A/C compressor discharge valve left open)
No | Go to the next step.
15 | INSPECT DRIVE BELT • Inspect drive belt. (See DRIVE BELT INSPECTION [MZI-3.7].) • Is it okay? | Yes | Go to the next step.
No | Adjust or replace drive belt, then go to Step 19.
16 | INSPECT DRIVE BELT CONDITION • Is drive belt worn? • Does it have foreign material imbedded in it, or have oil on it? | Yes | Remove obstruction, remove oil, or replace drive belt, then go to Step 19.
No | Go to the next step.
17 | INSPECT MAGNETIC CLUTCH • Inspect magnetic clutch. (See MAGNETIC CLUTCH INSPECTION.) • Is it okay? | Yes | Replace A/C compressor (excluding pressure plate, A/C compressor pulley, and stator), then go to Step 19.
No | Replace magnetic clutch, then go to Step 19.
18 | CHECK TO SEE WHETHER MALFUNCTION IS IN A/C COMPRESSOR OR REFRIGERANT LINES • Is noise emitted from A/C compressor? | Yes | Visually inspect A/C compressor, replace appropriate parts if necessary, then go to the next step.
No | If noise is due to refrigerant lines, repair detached or missing clips, tighten loose bolts, then go to the next step.
19 | VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR • Has A/C compressor noise stopped? | Yes | Troubleshooting completed. Explain repairs to customer.
No | Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.

* :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.