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Cooling

A Homeowner Guide to AC Diagnostics That Makes Sense

When your air conditioner isn't working right, it helps to understand what might be wrong before you call for service. A little basic troubleshooting can sometimes solve the problem yourself — and when it can't, it helps you describe the issue clearly to a technician.

AC not turning on. Check the thermostat first — make sure it's set to 'cool' and the temperature is set below the current room temperature. Check the circuit breaker; a tripped breaker is a common cause of a non-starting AC. Also check that the disconnect switch near the outdoor unit is in the 'on' position.

AC running but not cooling. If the system is running but the air isn't cold, check the air filter. A severely clogged filter can reduce cooling capacity significantly. Also check that all supply vents are open. If the filter is clean and vents are open, the problem may be low refrigerant, a dirty evaporator coil, or a failing compressor — all of which require a technician.

AC blowing warm air. This is often a refrigerant issue, but it can also be caused by a dirty condenser coil (the outdoor unit). Check that the outdoor unit is running and that the area around it is clear of debris. If the outdoor unit isn't running at all, the problem may be a capacitor or contactor failure.

AC cycling on and off frequently. Short cycling — where the system turns on and off every few minutes — is usually caused by an oversized system, a refrigerant problem, or a dirty evaporator coil. It can also be caused by a failing thermostat. Short cycling wastes energy and puts extra wear on the compressor.

Unusual noises. Banging or clanking usually indicates a loose or broken component. Squealing often points to a worn belt or bearing. Hissing can indicate a refrigerant leak. Any of these sounds warrant a service call.

Ice on the unit. See our article on frozen AC systems for a full explanation. The short version: turn the system off, let it thaw, check the filter, and restart. If it freezes again, call a technician.

West Coast Air Conditioning provides AC diagnostics and repair throughout Calaveras and San Joaquin County. Call (209) 598-8889.

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