If your AC runs but doesn't cool, the most common causes are a clogged filter, a failed capacitor, low refrigerant, a dirty or frozen coil, or a tripped outdoor unit. Start by checking the filter and thermostat. If that doesn't fix it, request a professional diagnosis - running it longer can worsen some issues.
Likely causes
| Cause | What's happening |
|---|---|
| Clogged air filter | Restricts airflow and reduces cooling; check and replace first. |
| Failed capacitor | Common Arizona summer failure; the fan or compressor may not start. |
| Low refrigerant / leak | Causes warm air and possible icing; needs professional service. |
| Frozen evaporator coil | Ice blocks airflow; turn the system off to thaw before service. |
| Dirty condenser coil | Outdoor unit can't release heat efficiently. |
- Indoor temperatures climbing dangerously during a heat wave
- Burning smell or smoke
- Repeated breaker trips
If anyone is in danger, or you smell gas, leave the home and call 911 or your utility immediately.
Frequently asked questions
What causes ac running but not cooling?+
Several issues can produce this symptom, from simple maintenance items to component failure. The likely causes table on this page lists what each cause looks like so you can describe the problem accurately when you request quotes.
Should I call someone right away?+
Call promptly if you see active water, no cooling during Arizona summer heat, burning smells, or repeated breaker trips. Otherwise, gather details and compare two written quotes before approving repairs.
Can PlumbAirAZ diagnose the problem?+
PlumbAirAZ is an Arizona plumbing and HVAC pricing and referral marketplace, not a contractor. We publish local price ranges and route your quote request to independent licensed service providers who contact you directly.
Related pages
Page Summary
- Topic
- AC Running but Not Cooling
- Location
- Arizona
- Best for
- Homeowners diagnosing the issue
- Primary action
- Request a professional diagnosis
- Related services
- See related pages
- Last reviewed
- June 2026
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Last reviewed: June 2026
PlumbAirAZ.com is a pricing, education, and referral marketplace. We do not perform the work unless expressly stated. Your request may be shared with or sold to independent HVAC, plumbing, or home service providers that may contact you about your project.