People who move to Phoenix usually arrive ready for the heat. They have heard about the 110°F afternoons and they know air conditioning is not optional here. What catches many newcomers off guard is how differently a cooling system behaves in the desert compared with the places they came from. Habits that worked fine in Chicago, Seattle, or even Southern California can lead to high bills, uncomfortable nights, and breakdowns at the worst possible moment.
The scale of a Phoenix summer explains why. National Weather Service records show the city logged 70 days at or above 110°F in 2024, the most on record, and a run of 113 straight days at or above 100°F. A system that works that hard for that long leaves very little margin for mistakes.
Here are seven that come up again and again in a newcomer’s first summer.
1. Expecting the AC to Hit Any Temperature You Set
On a 115°F afternoon, setting the thermostat to 68°F will not make the house colder faster. A central air conditioner removes heat at a fairly steady rate no matter what number is on the screen. A very low setting just keeps the system running without a break, which raises the bill and adds wear, and in extreme heat many systems simply cannot reach it.
A more realistic approach is to pick a comfortable setting in the high 70s, use ceiling fans to make that feel cooler, and let the system hold a steady temperature. If your home cannot hold a reasonable setting on hot afternoons, that is a sign to have the system checked, not a reason to turn the dial lower.
2. Shutting the AC Off When You Leave for the Day
In milder climates, turning the system off while you are at work saves money. In Phoenix, a house left without cooling all day absorbs a huge amount of heat into its walls, furniture, and attic. When you come home and turn the AC back on, it may run for hours trying to catch up, often during the late afternoon and evening, when electricity tends to cost the most.
Raising the thermostat a few degrees while you are away usually works better than turning it off. A programmable or smart thermostat makes this automatic. If you have pets at home, keeping the house cool is also a safety issue.
3. Forgetting the Air Filter During Monsoon Season
Summer in Phoenix also means monsoon season, when dust storms can sweep across the Valley and coat everything in fine grit. That dust goes straight into your HVAC system. A filter that might last a few months elsewhere can clog much sooner here.
A clogged filter restricts airflow, makes the system work harder, and can even cause the indoor coil to freeze. Check the filter every few weeks during the summer and replace it whenever it looks gray or dusty. It is the cheapest piece of maintenance you will ever do.
4. Not Learning How Your Utility Bills Work
Most Phoenix homes get electricity from APS or SRP, and both utilities offer several rate plans, including time-of-use plans where electricity costs more during certain hours of the day. New residents often stay on whatever plan came with the account and never look at it again.
Take a few minutes to read your plan and its peak hours. Many households lower their bills by cooling the home a little more before the peak window starts and letting the temperature drift up slightly during it. The right strategy depends on your plan, your schedule, and your home, so check the details with your utility.
5. Crowding or Ignoring the Outdoor Unit
The outdoor unit, called the condenser, releases the heat pulled out of your home. To do that, it needs open space and clean coils. Newcomers sometimes plant shrubs tight around it, stack storage against it, or let leaves and dust build up on the fins.
Keep a few feet of clear space around the unit on all sides. If the coil looks dirty, turn off power at the outdoor disconnect and rinse it gently with a garden hose. Avoid pressure washers, which can bend the thin metal fins. If the unit is on the roof, as many Phoenix systems are, leave that work to a professional.
6. Assuming Someone Else Already Checked the System
If you bought a home, the inspection report probably confirmed that the air conditioner turned on. That is not the same as knowing its age, refrigerant charge, or condition. A system that worked fine during a spring inspection can struggle once it faces its first real July.
Before your first summer, have the system inspected by a licensed local HVAC contractor. You can verify any contractor’s license through the Arizona Registrar of Contractors. Experienced Valley companies such as Adams Refrigeration, which has worked on Phoenix heating and cooling systems since 1947, know how desert heat and dust wear down equipment and what to look for in a home that is new to you.
Renters have a different situation, but it still helps to know the rules. Under the City of Phoenix cooling ordinance, rental units cooled by air conditioning must be able to keep habitable rooms at 82°F or below, and units with evaporative coolers at 86°F or below. If your AC stops working, notify your landlord in writing right away. Arizona law sets repair timelines, and they start from written notice.
7. Waiting for the First 110°F Day to Find a Problem
The worst time to discover your air conditioner has a weak part is the first truly hot week of the year, when HVAC companies across the Valley are already busy. A part that would have been an easy repair in April can mean a long, hot wait in late June.
Run your system in spring, before the heat arrives. Listen for new noises, check that air from the vents feels cool, and look at the outdoor unit. A spring checkup gives you time to fix small issues on your own schedule.
Your First-Summer Checklist
If you only remember a few things from this list, make them these:
- Set the thermostat to a realistic temperature and use ceiling fans.
- Raise the temperature a few degrees when you leave instead of turning the system off.
- Check the air filter every few weeks during summer.
- Learn your utility rate plan and its peak hours.
- Keep the outdoor unit clear and clean.
- Have the system inspected before your first summer.
- Test everything in spring, not on the first 110°F day.
Phoenix rewards people who plan ahead for the heat. A little attention to your air conditioner in your first year saves money, prevents surprises, and keeps your new home comfortable through even the longest summer.