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AC Making Strange Noises
in Spokane, WA
AC units make some noise when they run, but banging, grinding, or squealing are not normal. Those sounds mean a part inside is failing. Spokane's hot summers push units hard for weeks at a time, and that continuous run time wears motors and bearings faster. A noise that starts small usually gets worse quickly.
Quick Answer
Unusual noises from an AC almost always mean a moving part is worn or broken. A banging sound points to something loose inside the unit. A squeal usually means a bearing or belt is going. In Spokane, units that run hard through July and August wear out faster than average. Call (509) 472-2017 before a worn part fails completely and takes other parts with it.
Telltale Signs
Warning Signs to Watch For
- A banging or clanking sound when the unit starts up or runs
- A high-pitched squeal or screech from the outdoor unit
- A grinding noise that gets louder over several days
- Rattling when the fan runs that wasn't there last summer
- A clicking sound that repeats over and over without the system starting
- A hissing sound near the refrigerant lines
Root Causes
What Causes AC Making Strange Noises?
Loose or Broken Fan Blade
The outdoor fan blade can crack or come loose from the motor hub over years of hard use. When it's loose, it wobbles and hits the inside of the unit. Spokane's temperature swings from below freezing in winter to over 100 in summer expand and contract metal parts, and fasteners can work loose over time.
The Fix
Fan Blade Inspection and Replacement
A tech shuts power to the unit, inspects the blade and motor hub, and replaces any damaged parts. Running with a loose blade can bend the blade further or damage the motor shaft.
Failing Motor Bearings
Both the indoor blower motor and the outdoor fan motor have bearings that allow them to spin smoothly. When bearings wear out, they grind or squeal. Units in Spokane that run 12 or more hours a day during July heat waves put extra hours on those bearings and wear them out faster.
The Fix
Motor Bearing Replacement or Motor Replacement
Sometimes bearings can be lubricated to extend their life, but worn bearings usually need the motor replaced. Catching it at the squealing stage is better than waiting for the motor to seize.
Refrigerant Leak Hissing
A hissing sound near the refrigerant lines or outdoor unit often means refrigerant is escaping through a small hole or a loose fitting. This is different from other noises because it's steady and doesn't change with the fan speed.
The Fix
Leak Detection and Line Repair
A tech uses a leak detector to find the exact spot, repairs or replaces the damaged section, and recharges the system. Hissing leaks don't seal themselves and will get larger.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Loose or Broken Fan Blade | Failing Motor Bearings | Refrigerant Leak Hissing |
|---|---|---|---|
| Banging sound starts immediately when the outdoor unit kicks on | |||
| High-pitched squeal that gets worse as the unit warms up | |||
| Steady hissing sound near the copper lines at the outdoor unit | |||
| Rattling that changes pitch when you cover one vent | |||
| Grinding sound that started after a long hot stretch in late July |
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