New to Phoenix? What Nobody Tells You About HVAC Here
If you moved here from somewhere with four seasons, several things about running a house are genuinely different.
New Phoenix homeowners should know that air conditioners run roughly eight months a year and last 10 to 15 years rather than 15 to 20, filters need changing every 30 to 60 days, maintenance is needed twice annually, and the system is expected to run nearly continuously on days above 110°F.
The system runs almost constantly, and that is fine
People arriving from temperate climates frequently worry that something is wrong because the air conditioner never seems to shut off in July.
Equipment here is sized to a design temperature around 108 to 110 degrees. On days hotter than that, continuous operation is expected and is in fact easier on the equipment than frequent cycling.
The question is not whether it runs constantly. It is whether it holds the temperature while running. Drifting a degree or two on a 117-degree afternoon is normal. Drifting eight is a problem.
Things that are different here
| Temperate climate | Phoenix | |
|---|---|---|
| Cooling season | 3–4 months | About 8 months |
| Equipment life | 15–20 years | 10–15 years |
| Filter changes (1") | Every 90 days | Every 30–60 days |
| Professional maintenance | Once a year | Twice a year |
| Typical summer setpoint | 72–74°F | 78–80°F |
| Main HVAC concern | The furnace | The air conditioner |
| Attic temperature | 110–130°F | 150–160°F |
Learn where five things are
- The filter, or filters. Many Valley homes have more than one, and people change one for years without finding the other. Note the sizes.
- The outdoor disconnect. A small box beside the condenser. It kills power to the outdoor unit safely.
- The indoor service switch. Looks like a light switch near the air handler or furnace.
- The condensate drain access. A PVC tee with a cap near the indoor unit, where you pour vinegar monthly.
- The breaker for the HVAC in your panel.
Twenty minutes finding these now is worth a great deal at 9pm in July when something goes wrong.
The habits that matter most
- Change the filter every 30 to 60 days. Set a phone reminder; the calendar will not remind you.
- Pour a cup of distilled white vinegar into the condensate drain monthly during cooling season.
- Rinse the outdoor coil gently with a hose a couple of times a season, power off at the disconnect first.
- Keep two feet clear around the outdoor unit and trim landscaping back.
- Schedule maintenance twice a year — spring for cooling, fall for heating.
- Set the thermostat at 78 to 80 and leave it rather than chasing it down on hot days.
- Close blinds on sun-facing windows before the sun reaches the glass.
Yes, you need heat
New residents are consistently surprised by this. Valley overnight lows reach the upper 30s regularly in December and January, and outlying areas run colder still.
Your heating equipment sits unused from March to October, which means the first genuinely cold night produces a wave of no-heat calls across the metro from people whose furnaces have not run in seven months.
Run the heat deliberately for fifteen minutes on a warm October afternoon with the windows open. You clear the dust burn-off smell and, more importantly, discover any problem while it is an inconvenience.
Monsoon changes things
From roughly July through September, humidity rises. That has three practical effects.
The house feels muggier at the same thermostat setting, because more of your system's capacity goes to removing moisture. Set the fan to AUTO rather than ON — running the blower after the compressor stops re-evaporates moisture back into the house.
Your system produces far more condensate, so the drain matters more. Monthly vinegar is not optional during monsoon.
And dust storms pack the condenser coil and load filters in a single afternoon. Check both after any significant haboob.
Heat safety is real
This is the part worth taking seriously. If the air conditioning fails in July, an unconditioned Valley house becomes genuinely dangerous within hours — particularly for adults over 65, infants, anyone with a cardiovascular condition, anyone on medications affecting thermoregulation, and pets.
Have a plan. Know where you would go. Give a neighbor your number. And if a system fails and the house is climbing past the mid-90s with vulnerable people in it, leave rather than waiting for a technician.
That is not an overreaction here. It is the correct response.
Frequently asked
Is it normal for my A/C to run all day in Phoenix?
Yes, on days above about 110°F. Equipment is sized to a design temperature around 108 to 110, so continuous operation on hotter days is expected and is easier on the equipment than frequent cycling. The question is whether it holds temperature while running.
How often should I change my air filter in Phoenix?
Every 30 to 60 days for a one-inch filter, closer to 30 during dust storm season or with pets. Four- and five-inch media filters last six to twelve months. Check after any significant dust event regardless of the calendar.
Do I need heating in Phoenix?
Yes. Valley overnight lows reach the upper 30s regularly in December and January, and outlying areas run colder. Because the equipment sits unused from March to October, run it deliberately in October to find problems before the first cold night.