Honda Accord: A/C System Noise Check - Heating/Air Conditioning - Heating, Ventilation, and Air Conditioning - Honda Accord MK8 2008-2012 Service ManualHonda Accord: A/C System Noise Check

• Air conditioning refrigerant or lubricant vapor can irritate your eyes, nose, o r throat.

• Be careful when connecting service equipment.

• Do not breathe refrigerant or vapor.

The A/C system noise check w i l l help you determine the source of abnormal A/C s y s t em noise.

NOTE: • If an accidental system discharge occurs, ventilate the work area before resuming service.

• Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers.

• Identify the conditions when the noise occurs. The weather, the vehicle speed, the vehicle being in gear or in neutral, the engine temperature, or other conditions may be factors in determining the noise source.

• Do an A/C system inspection (see page 21-8), and correct any problems found prior to diagnosing abnormal noises.

• Abnormal A/C noises can be misleading. For example, a sound similar to a failed bearing may be caused by loose fasteners, loose mounting brackets, or a faulty A/C compressor clutch assembly.

1. Inspect the air inlet grille in the cowl cover for debris.

If debris is present, remove it.

2. Sit inside the vehicle, close the doors and windows, and turn the ignition switch to ON (II), but do not start the engine. Cycle the HVAC system through all blower speeds and all air distribution modes to determine where and when the noise occurs.

3. Operate the blower at each speed with the engine and A/C off, and check for unusual noises and excessive vibration. If noise and/or vibration are present, do the following checks: -1. If the noise or vibration occurs only in a specific mode or setting, then check these items: o Operation of the mode control motor, door, and linkage.

• Operation of the air mix control motor(s), door(s), and linkage.

• Operation of the recirculation control motor, door, and linkage.

-2. If there is a squeaking or chirping noise, but no unusual vibration, replace the blower motor (see page 21-67).

-3. Remove the blower unit (see page 21-65), and check for foreign material (leaves or twigs, for example) on the blower motor and fan. If foreign material is present, remove it, and recheck for noise. If you don't find any foreign material, remove the blower motor (see page 21-67), and check these items: • Check if the fan blades are cracked or broken.

• Make sure the fan retainer is tight.

• Inspect the fan alignment on the blower motor shaft.

Replace the blower motor if any problems are present.

4. Set up the vehicle for the running A/C checks: • Select a quiet area for testing.

• Apply the parking brake.

• Shift the vehicle in Por N (A/T), or in Neutral (M/T).

• Start the engine.

• Set the temperature control dial to Max Cool.

• Set the mode control switch to Vent.

• Set the fan control dial to minimum (but not OFF).

• Turn the A/C switch ON.

Switch the A/C compressor on and off several times to clearly identify the sound during A/C compressor operation. Listen to the noise while the A/C compressor clutch is engaged and disengaged. Probe the A/C system with a stethoscope to pinpoint the noise.

NOTE: If the noise does not change when the A/C compressor clutch engages or disengages, the noise may be caused by an engine-related component.

Probe the engine area with a stethoscope to pinpoint the noise.

5. Turn the Ignition switch to LOCK (0), and check the drive belt for excessive wear, oil contamination, improper routing, or a faulty belt tensioner (see page 4-30). Correct any problems found. Start the engine, run the A/C system, and check if the noise is coming from the drive belt, the belt tensioner or any of the pulleys. Repair or replace any faulty components.

6. Listen for noises coming from the A/C lines, the A/C hoses, the A/C condenser, the evaporator, the receiver-drier, or the expansion valve, and check these items: • Noises caused by A/C components touching other components or the body. Reroute or insulate the A/C component(s) as needed, and recheck for noise.

• Loose, damaged or excessively worn A/C components or mounting hardware. Repair or replace the faulty component(s) or hardware, and recheck for noise.

• A moaning noise coming from the A/C suction line.

If there is a moaning noise, check the system refrigerant charge (see page 21-81). If the refrigerant charge is OK, replace the receiver/dryer.

7. Check the operation of the A/C compressor clutch: • Make sure A/C compressor clutch engages without slipping. If the clutch does not engage, troubleshoot the A/C compressor clutch circuit (see page 21-52).

If the A/C compressor clutch slips, replace the complete clutch assembly (see page 21-75).

• Make sure the A/C compressor clutch disengages. If the clutch does not disengage, do the A/C compressor clutch check (see page 21-73). If the A/C compressor clutch is OK, replace the A/C compressor (see page 21-72).

• Make sure the A/C compressor clutch cycles normally. If the A/C compressor clutch is cycling rapidly, the A/C system is probably low on refrigerant due to a leak. Do the refrigerant leak check (see page 21-82). If the refrigerant charge is OK, and there are no leaks, troubleshoot the A/C compressor clutch circuit.

8. Listen with a stethoscope for noises coming from the A/C compressor, and check these items: • The noise changes when the A/C compressor clutch disengages. If the noise does not change when the A/C compressor disengages, the noise may be caused by an engine-related component. Probe the engine area with a stethoscope to pinpoint the noise.

• The A/C system operating pressures are normal. If the system pressures are abnormal, troubleshoot the problem using the pressure test table in the A/C system test (see page 21-89). Correct the pressure-related problem(s), and recheck for noise.

• The A/C compressor hose connections, mounting brackets, and fasteners are in good condition. If any of these components are loose, damaged, or excessively worn, repair or replace the faulty component(s), and recheck for noise. If these components are in good condition, and the noise is still present, replace the A/C compressor (see page 21-72).

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