Why Is My AC Running But Not Cooling in Arizona? 5 Common Causes

When your air conditioner is running but your house still feels like an oven, it’s easy to feel frustrated—especially during a blazing summer in Mesa or Tucson.

AC issues in Arizona aren’t just inconvenient; they can be dangerous when temperatures soar. If your central air isn’t blowing cold air, don’t panic.

Here are five of the most common reasons Arizona homeowners run into this issue—and what to do next.

If your home isn’t cooling down and none of the fixes below help, it might be time to schedule AC repair in Mesa or Tucson with our experts at Western States Home Services.

1. Dirty or Clogged Air Filter

How Filters Affect Cooling

Your AC needs clear airflow to function efficiently. When your air filter is clogged with dust, pet hair, or debris, it chokes off that airflow—making it much harder for your AC to push cool air through your vents.

This can cause your system to run constantly without effectively cooling your space. It also increases energy bills and puts unnecessary strain on your system, leading to more frequent breakdowns.

How Often to Replace Filters in AZ’s Dusty Climate

In Arizona’s dry, dusty environment, filters clog up faster than in other areas. We recommend checking your air filter at least once a month and replacing it every 30 to 60 days—especially if you live in Mesa or Tucson, have pets, or run your system daily.

2. Low Refrigerant Levels

Signs of a Refrigerant Leak

If your system is low on refrigerant, it can’t absorb heat from inside your home effectively. Common signs include:

• Warm or lukewarm air coming from your vents
• Ice buildup on your refrigerant line or outdoor unit
• Hissing or bubbling sounds from your AC
  

Why Leaks Are Common in Arizona Heat

Refrigerant doesn’t get “used up”—if it’s low, there’s likely a leak. High outdoor temperatures in Arizona can cause components to expand and contract more frequently, putting added stress on refrigerant lines and connections.

If you suspect a leak, schedule AC service in Mesa or AC service in Tucson immediately. Leaking refrigerant isn’t just inefficient—it can be hazardous to your health and harmful to the environment.

3. Frozen Evaporator Coil

What Causes Freezing?

It might sound strange, but a frozen coil can cause your AC to stop blowing cold air. When airflow is restricted—often from a dirty filter or low refrigerant—the evaporator coil can get too cold and freeze over.

Signs Your Coil Is Frozen

You may notice ice forming on the coil itself, visible through vents or access panels. Another sign is a noticeable decrease in airflow or completely warm air coming from your system.

To prevent this issue, stay on top of filter changes and call for HVAC service if your refrigerant seems low.

4. Dirty Condenser Coils

The Role of Your Outdoor Unit in Heat Removal

The outdoor condenser coil is responsible for releasing the heat your system pulls from inside your home. But if it’s covered in dust, leaves, or yard debris—a common issue in Arizona’s dusty, windy climate—it can’t do its job.

Cleaning Tips for Arizona Homeowners

Turn off power to the unit before cleaning. Use a soft brush or hose (not pressure washers) to gently rinse off debris. Keep at least two feet of clearance around the unit.

If it looks especially dirty or you’re unsure, don’t risk damaging the system—call a pro for a proper deep clean. We handle full AC inspections and repairs in Mesa and Tucson.

5. Thermostat Problems or Wrong Settings

Check Fan Mode, Schedule, and Battery

Sometimes, the issue isn’t the AC—it’s the thermostat. Double-check that your system is set to “cool,” the fan is set to “auto,” and that the batteries (if applicable) are still good. Smart thermostats can also reset or glitch, especially after power surges.

Smart Thermostats for Extreme Climates

For Arizona homes, a smart thermostat with heat-adaptive scheduling can help prevent issues caused by setting conflicts or irregular usage. Western States can help with recommendations and upgrades.

When to Call a Pro (Especially in AZ’s Harsh Summer)

If you’ve checked your filter, verified your settings, and your AC is still not cooling your Arizona home, it’s time to call in the pros.

Whether you’re in Mesa or Tucson, we’ll get to the root of the issue fast—so your home can feel like a sanctuary again. Our team offers expert diagnostics, transparent pricing, and same-day air conditioning repairs when you need them most.

Contact us now to book your appointment!

Customer Q&A: Common Air Conditioner Problems