Air Conditioner Making Noise in Greater Vancouver

An air conditioner that develops new or unusual sounds should be investigated — most AC sounds point to a specific mechanical issue that is easier and less expensive to fix before it leads to a larger failure.

What This Means

AC systems have two main noise sources: the outdoor condensing unit and the indoor air handler. Identifying which unit is making the noise and what it sounds like narrows the diagnosis significantly.

Common Causes

• Outdoor unit rattling — debris in the condenser cabinet (leaf, stone, small branch)
• Outdoor unit screeching — condenser fan motor bearing failing
• Outdoor unit banging — loose or damaged fan blade, or compressor internal knock
• Indoor unit squealing — blower motor bearing failing or blower wheel hitting the housing
• Indoor unit ticking — debris in the blower wheel
• Bubbling or gurgling — refrigerant flowing through a restriction or expansion valve

What Homeowners Can Check Safely

• Turn off the outdoor unit and inspect for visible debris through the fan grille
• Check the indoor air handler blower door is properly closed — a loose door causes rattling and reduces efficiency

When to Call a Licensed Technician

Air conditioning and mini-split systems contain refrigerant under pressure and electrical components at line voltage. Do not open refrigerant circuits, attempt to recharge the system, or bypass safety controls — these require a certified technician.

• Condenser fan motor bearing inspection and replacement
• Fan blade inspection and balancing or replacement
• Blower motor bearing inspection
• Refrigerant restriction diagnosis if bubbling persists

Frequently Asked Questions

My air conditioner makes a loud bang when it starts up. Is that normal?

A brief click at startup from the contactor engaging is normal. A loud metallic bang at startup can indicate: a compressor with valve issues causing an abrupt pressure differential at startup, or a loose component that shifts when the unit vibrates. A loud bang that was not there before should be investigated before the unit fails at a less convenient time.

Why does my AC indoor air handler make a whistle noise?

Whistling from the air handler is almost always caused by high airflow velocity through a restriction — usually a severely loaded filter or a partially closed supply register. Replace the filter first. If whistling persists with a clean filter, check that all supply registers are fully open.

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