What To Do When Your AC Is Running But Not Cooling in Peoria, AZ

Logan McQueen

If your air conditioner is running but not cooling, the most common culprits include a dirty air filter, incorrect thermostat settings, restricted airflow, a frozen evaporator coil, or a failing capacitor. Homeowners in Peoria and the Northwest Valley can safely start by checking the filter, confirming thermostat modes, and ensuring vents are open. If the system is iced over or still not cooling after basic checks, it’s time to bring in the pros at HilCo Mechanical.

Why Is My AC Running But Not Cooling?

In the Arizona heat, a running AC that isn’t cooling can feel like an emergency. The good news is that many issues have simple fixes—while others require a licensed technician to prevent damage to your system. Here’s how to tell the difference.

1. A Dirty or Clogged Air Filter

A dirty filter is the #1 cause of weak or warm airflow. When it becomes clogged, your HVAC system can’t pull in enough air to cool properly, and the evaporator coil may even freeze.

Safe homeowner steps:

  • Turn off the system and check the air filter.
  • Replace the filter if it’s dirty or hasn’t been changed in 30–60 days.

2. Incorrect Thermostat Settings

Sometimes the solution is as simple as switching the thermostat back to “Cool” or lowering the set temperature.

Safe homeowner steps:

  • Confirm the thermostat is set to “Cool,” not “Fan” or “Heat.”
  • Make sure the temperature is set several degrees below the indoor reading.
  • If the thermostat screen is blank or slow to respond, replace the batteries.

3. Airflow Restrictions

Closed vents, obstructed returns, or a blocked outdoor condenser can all prevent proper cooling.

Safe homeowner steps:

  • Ensure all supply vents are open—especially in rooms far from the thermostat.
  • Remove furniture, rugs, or boxes blocking return vents.
  • Visually check the outdoor unit for debris, leaves, or landscaping growing too close.

4. Frozen Evaporator Coil

If you notice ice on the refrigerant lines or your AC stops blowing air altogether, the evaporator coil may be frozen. This can happen from airflow problems, low refrigerant, or mechanical issues.

Safe homeowner steps:

  • Turn the system off and switch the thermostat to “Fan” mode to speed up thawing.
  • Do NOT try to chip or remove ice manually.

When to call a pro: If the coil freezes again, you likely have a refrigerant or component issue that must be diagnosed by a trained technician.

5. Electrical or Capacitor Problems

Your AC uses capacitors to start and run the compressor and fan motors. When they weaken or fail, the system may run but won’t cool effectively.

Signs include:

  • AC makes a buzzing or humming sound
  • The outdoor fan isn’t spinning
  • AC shuts off unexpectedly

Homeowner warning: Capacitors store electricity and can be dangerous. Do not attempt to repair or test them yourself.

When It’s Time to Call HilCo Mechanical

If your AC is still not cooling after checking the basics, it’s time for a licensed HVAC technician. HilCo Mechanical has served Peoria, AZ and the Northwest Valley since 1989, and we’re available 24/7 for urgent cooling issues.

What to Expect From a Professional Service Call

  • Full system diagnostic – We test electrical components, refrigerant pressures, and airflow.
  • Clear explanations – We show you what we found and explain your options in plain language.
  • No-pressure recommendations – Whether it’s a repair or long-term solution, we help you decide what’s best.
  • Fast, honest service – Our family-owned team treats customers like neighbors, not transactions.

Need Fast AC Repair in Peoria or the Northwest Valley?

If your AC is running but not cooling—and Arizona heat is rising—our team is ready to help day or night. Learn more about our AC repair services here: AC Repair.

Have a question or need same-day service? Reach out anytime: Contact Us.

Call or text HilCo Mechanical 24/7—we’re here to keep your home cool and comfortable.