AC Stopped Cooling in a Phoenix Heat Wave? Do This First

What should I check first when my AC is not cooling?

Run these in order. Each step takes a minute or two, and none requires opening anything.

Minutes 0-5: the easy ones

1. Set the thermostat to Cool, a few degrees below the current room temperature. Swap in fresh batteries if the display is dim.
2. Check your breaker panel. If the AC breaker is tripped, reset it once.
3. Pull the filter. If it's gray and clogged, replace it. The Department of Energy recommends cleaning or replacing filters monthly in peak-use seasons.^[4]

Minutes 5-10: look outside 4. Look at the outdoor unit from a safe distance. Clear leaves, trash or monsoon debris from around it. Then note whether the fan is spinning, humming or completely silent.

Minutes 10-15: check the air 5. Hold your hand at a vent. Is air moving, and is it cool or warm? Strong cool air means the system is working, while weak or warm air points to a problem.

Stop rules matter here. If the breaker trips a second time, you see ice, or you smell burning, shut cooling off and call.

Timeline

The 15-minute check

1. Minutes 0-5

   Thermostat, breaker and filter

2. Minutes 5-10

   Look at the outdoor unit

3. Minutes 10-15

   Check the air at a vent

For a deeper look at warm air, see why your AC blows warm air.

Why is my AC on but not cooling the house?

A running system that isn't cooling usually has restricted airflow, a dirty or frozen coil, a failed capacitor or fan motor, or low refrigerant. A dirty filter can starve the indoor coil of air until it ices over. The Department of Energy also notes that an improper refrigerant charge cuts cooling capacity and efficiency.^[5]

Here is how to read what you see:

• Outdoor fan not spinning, indoor air still blowing: often a capacitor or fan problem. Technician-only. See AC fan not spinning.
• Weak airflow, frost on the lines: a frozen coil. Turn cooling off and call. More in why an AC freezes up.
• Outdoor unit humming but nothing moves: technician-only.
• Weak airflow, dirty filter: homeowner-fixable.
• Unit starts and stops repeatedly: see AC short cycling.

Why won't my AC get colder than 72?

Phoenix summer highs average around 106°F, and a system can fall behind on the hottest afternoons without being broken. The clue is a unit that runs constantly and loses ground only at peak heat. That can point to aging or undersized equipment, leaky ducts or poor attic insulation.

Ask the technician to check capacity and measure the temperature drop across the coil.

If your home uses a swamp cooler instead, none of this applies.

What should I not do when my AC stops cooling?

• Don't open the outdoor cabinet or touch capacitors. They can hold a stored electrical charge.
• Don't spray water on the condenser. Water plus live wiring is a shock risk.
• Don't keep resetting the breaker. A repeat trip signals an electrical fault.
• Don't run a frozen unit. Switch to fan-only to help it thaw, then call.
• Don't buy refrigerant online. Handling it requires EPA Section 608 certification, and low refrigerant means a leak that needs finding. See recharge kits vs. a pro recharge.
• Don't hire an unlicensed "handyman." HVAC work needs an Arizona Registrar of Contractors license in the R-39, R-39R or CR-39 class. The handyman exemption covers only minor work under $1,000 that needs no permit and has no fuel connection.

How do I keep my family cool while I wait for repair?

Phoenix logged 113 straight days at 100°F or higher in 2024. A dead AC is a health risk, not just discomfort.

Move everyone to the lowest, shadiest interior room. Close blinds on west and south windows. Run fans only while people are in the room, drink water and take cool showers. Keep pets, medications and electronics with you.

Know the early warning signs. Maricopa County lists dizziness, nausea, headache, heavy sweating and weakness. Move to a cooler place, hydrate, and get medical help if symptoms worsen.^[1]

If the house becomes unsafe, leave. Call 2-1-1 to locate cooling sites, which the county has coordinated in Phoenix, Glendale, Chandler, Mesa and Tempe.^[2][6] A friend's air-conditioned home works too.^[3]

What do I tell the dispatcher when I call?

Have this ready. Fill in the brackets.

It's a [central split / package unit], about [age] years old. The thermostat reads [X] and is set to [Y]. The outdoor fan is [running / not]. Air from the vents is [warm / cool]. The breaker is [on / tripped once]. There is [an infant / senior / pet] in the home, and it's [X] degrees inside."

Mention ice, water or burning smells if you've seen them. Then ask:

• What is the arrival window?
• What are the diagnostic fee terms? One Phoenix-area company-site survey found most list $70 to $90, and some waive or credit it if you approve the repair (Phoenix-area HVAC companies' own websites, checked October 2026).
• Will I get a written estimate before work starts?
• What is your ROC license number, and can you show proof of liability coverage?

Verify the license through the Contractor Search at roc.az.gov/before-hire, and confirm the class covers HVAC. Our guide to verifying an HVAC license walks through it.

Checklist

Ask before you book

0 of 5 ticked

• What is the arrival window?
• What are the diagnostic fee terms?
• Will I get a written estimate before work starts?
• What is your ROC license number?
• Can you show proof of liability coverage?

Tick them off as you go. Nothing is saved or sent.

When should I call for same-day AC service in Phoenix?

Call now if any of these apply: no cooling after the basic checks, the breaker trips again, there's ice, a burning smell or leaking water, the outdoor unit is dead, or the house is heating quickly. Also call now if an infant, senior or pet is at home.

A scheduled visit is fine only if the house stays safe and the problem looks minor, such as a clogged filter you've already replaced.

Scheduling can get tight in late spring and after monsoon storms, so book early.

On cost, one Phoenix company's site says minor repairs typically run $150–$500 and major component repairs $1,000–$3,000+. Get an itemized written quote. See AC repair costs in Phoenix.

Sample document

Sample price ranges

Estimate

Sample

• Diagnostic fee$70 to $90
• Minor repair$150–$500
• Major component repair$1,000–$3,000+

Illustrative figures, not a quote.

Repairs generally need no permit, but replacement rules differ by city. Phoenix requires none for like-for-like replacement that doesn't increase size, capacity or location. Mesa needs none if the new unit uses the same or less electricity. Scottsdale requires a Minimum Mechanical Permit even for like-for-like. For Tempe, Chandler, Gilbert and Glendale, ask your city.

Ready to book? Use emergency 24-hour AC repair.

Frequently asked questions