There's nothing like realizing your AC quit on the hottest day of the year, and nine times out of ten, the fix is smaller than you'd think.
Most of the time, a broken AC isn't actually broken, it's a dirty filter, a tripped breaker, or the thermostat set wrong. Check those three first, they take under ten minutes combined and cost nothing. If the system still won't cool after that, you're likely looking at a real AC repair, refrigerant, a capacitor, or the compressor, and that's when it's time to call an HVAC technician.
According to HVAC pros, a dirty filter alone accounts for the overwhelming majority of "my AC isn't working" calls. Before you assume the worst, work through the free checks first.
Confirm it's set to "cool," not "fan" or "heat," and that the target temperature is actually lower than the current room temperature. If the display is blank, swap the batteries before assuming anything electrical has failed.
A clogged filter restricts airflow so badly the system can't cool effectively, and in the worst cases causes the evaporator coil to freeze over entirely. Filters cost $5-20 and take under five minutes to swap. If you can't remember the last time you changed it, this is almost certainly your answer.
If the rest of your house has power but the AC won't turn on at all, check the breaker panel and reset it if it's tripped. A breaker that trips repeatedly, rather than just once, points to a deeper electrical issue and is a sign to call an electrician or HVAC tech rather than keep resetting it.
| Symptom | Likely cause | Typical repair cost |
|---|---|---|
| Blows warm air | Low refrigerant, dirty condenser coils | $200 – $700 |
| Ice on the coils or lines | Frozen evaporator coil (often from restricted airflow) | $150 – $500 |
| Won't turn on, breaker holds | Failed capacitor or contactor | $150 – $400 |
| Runs but doesn't cool | Compressor issue | $600 – $3,000+ |
| Water pooling near indoor unit | Clogged condensate drain line | $100 – $300 |
Nationally, AC repair costs range from $130 to $3,000, with most homeowners landing around $350 for a typical repair. The wide range comes down almost entirely to which specific component failed.
Hissing, buzzing, grinding, or a burning smell coming from your AC means stop and shut it off right away, don't wait to see if it resolves itself. These signs typically point to a refrigerant leak, a failing motor, or an electrical issue, all of which can turn into a much bigger repair, or a safety hazard, if the system keeps running.
Beyond the filter, your outdoor condenser unit benefits from a simple cleaning: clear away leaves, grass clippings, and debris, and gently hose off the exterior fins without bending them. A dirty condenser makes the whole system work harder and can meaningfully reduce cooling efficiency even before it fully fails. This is genuinely DIY-friendly and worth doing once a season.
Know what's DIY-safe and what needs a pro before you start troubleshooting
Refrigerant work legally requires an EPA-certified technician, it's not a DIY project regardless of your comfort level with tools. Capacitors and contactors involve live electrical components capable of storing a dangerous charge even when the unit is off. The compressor is the single most expensive part in the whole system, and diagnosing it correctly the first time is worth paying for rather than guessing and potentially damaging it further.
Most filters last 1-3 months depending on usage, and up to 12 months for some higher-end filters. Homes with pets, allergies, or systems running constantly during peak summer should check more frequently.
This usually points to low refrigerant, a dirty condenser or evaporator coil, or a failing compressor, all of which reduce the system's ability to remove heat even though the fan and power are working normally.
Yes, in most cases. Running a struggling system, especially one with a frozen coil or failing compressor, often causes additional damage and turns a moderate repair into a much more expensive one. Turn it off and diagnose the issue first.
Yes. An annual professional tune-up catches small issues, a weak capacitor, a slow refrigerant leak, before they become full breakdowns, and it's considerably cheaper than an emergency repair on the hottest day of summer.
Most homeowners fund larger home repairs through the equity already sitting in their home rather than paying it all out of pocket at once.
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