Home Troubleshooting

AC troubleshooting: what's actually wrong

Almost every home-AC failure traces back to one of these nine. Each is explained by what it does to the refrigeration cycle — so you understand the fix instead of just parroting it.

🌫️

Why does a dirty air filter stop your AC from cooling?

The filter clogs with dust and chokes the airflow across the indoor coil.

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DIY
💧

Why is my AC low on refrigerant?

A leak somewhere in the sealed loop. Refrigerant is never 'used up' — if you're low, it escaped.

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Call a pro
🍂

What happens when your outdoor AC coil gets dirty?

The outdoor coil gets caked with dirt, grass clippings, cottonwood, and leaves.

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DIY / pro
🧼

Why does a dirty indoor coil kill your cooling?

Dust slips past a cheap or missing filter over months and coats the indoor coil.

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Call a pro
🧊

Why is my AC's evaporator coil frozen?

Almost always a symptom of something else: low airflow (dirty filter or weak blower) or low refrigerant.

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DIY first aid + pro
💔

How do you know if your AC compressor is failing?

Age, an electrical fault, chronic overheating, or liquid refrigerant slugging back and damaging it.

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Call a pro
🔋

What are the symptoms of a bad AC capacitor?

Capacitors store and release the electrical jolt that starts and runs the compressor and the fan motors. Heat and age make them weaken, bulge, and fail — it's one of the single most common AC breakdowns, especially in a heat wave.

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🚪

What happens when the expansion valve sticks?

Debris, moisture freezing inside it, or a failed sensing bulb on the expansion valve.

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📈

Can you put too much refrigerant in an AC?

Someone added more refrigerant than the system is rated for — more isn't better.

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Start here if you're not sure

Two symptoms cover most calls. Ice on the coil is almost always airflow or refrigerant — start with the frozen coil guide. An outdoor unit that hums but won't spin is very often a failed capacitor, a cheap part that mimics far more expensive failures.

Not sure what the parts even do? The interactive cycle diagram walks through all four stages in about two minutes.