Top 5 Most Common HVAC Problems
Why is my AC not blowing cold air?
- Clogged air filter: A dirty filter throttles airflow across the evaporator coil, so the air reaches your vents lukewarm.
- Low refrigerant charge: Tiny leaks let refrigerant escape, shrinking the system’s cooling capacity.
- Outdoor unit issues: A blocked condenser coil or failed fan can’t dump heat outside.
- Thermostat mis-set or faulty: “On” instead of “Auto,” bad batteries, or a miscalibration can all trick you into thinking the system’s running but not cooling.
Quick fix: Replace the filter, clear debris around the outdoor coil, and double-check thermostat settings. If that doesn’t restore chill, call a pro to test refrigerant levels and inspect the compressor.
Why is my AC leaking water?
- Condensate drain clog: Dust and algae plug the drain line, sending condensation back into the air handler and onto your floor.
- Broken drain pan: Metal pans rust; plastic ones crack—both send water where it shouldn’t go.
- Ice melt-off: After a freeze-up (see next section), the thaw can overwhelm the drain.
Quick fix: Flush the drain line with a wet/dry vac or vinegar solution, then replace damaged pans. Persistent leaks may point to low refrigerant or airflow problems that a technician should diagnose.
Why is my AC freezing up?
- Airflow restrictions: Dirty filters, closed vents, or a failing blower motor let condensation linger and freeze on the coil.
- Low refrigerant: Less pressure = lower coil temperature = ice.
- Thermostat set too low: Running the system hard on mild days can drop coil temps below freezing.
Quick fix: Shut the system off to thaw (fan-only mode speeds this up), swap in a clean filter, and open supply vents. If ice reappears, have a technician hunt for refrigerant leaks or blower issues.
Why is my AC not turning on?
- Tripped breaker or blown fuse: A power surge or over-amp draw cuts juice to the unit.
- Thermostat malfunctions: Dead batteries, loose wiring, or misprogrammed schedules keep the call for cooling from reaching the control board.
- Clogged condensate safety switch: Water in the drain pan trips a float switch and shuts the system down to prevent overflow.
- Failed capacitor or contactor: These electrical parts kick-start the compressor and fans; when they die, nothing happens.
Quick fix: Reset breakers, replace thermostat batteries, and empty the drain pan. If there’s still radio silence, it’s time for a pro to test electrical components.
Why is my AC so loud?
- Loose panels or screws: Vibrations make sheet metal rattle.
- Worn fan motor bearings: A screech or grinding points to bearings on their last legs.
- Refrigerant whistle or hissing: High-pressure leaks make a tell-tale sound and demand immediate attention.
- Debris in the blower or outdoor fan: Twigs, leaves, or ice can clack against blades.
- Ductwork expansion pops: Temperature swings flex metal ducts, creating bangs that echo through vents.
Quick fix: Tighten panels, clear debris, and replace filters. Persistent screeches, hisses, or grinding noises mean a technician should inspect motors and refrigerant lines.
