For most Phoenix homes, central air conditioning is the better main cooling system, and an evaporative cooler works best as a low-cost partner for the dry months. In the evaporative cooler vs AC debate, cost favors the cooler. The U.S. Department of Energy says evaporative coolers cost about half as much to install as central AC and use about one quarter of the energy. The catch is humidity. Once Phoenix dew points climb above about 55 degrees during monsoon season, a swamp cooler loses much of its cooling power and can leave the house damp. Central AC holds your set temperature through 115 degree afternoons and humid August nights alike.
Adams Refrigeration has cooled Valley homes since 1947, through the decades when swamp coolers sat on most Phoenix roofs and the shift to refrigerated air that followed. We are a Carrier Factory Authorized Dealer, licensed under Arizona ROC 245268. Here is how the two systems compare on cost, comfort, water, and upkeep, and how to decide which fits your home.
How Each System Cools
The two systems cool your home in very different ways. That difference explains almost every pro and con that follows.
How an Evaporative Cooler Works
An evaporative cooler, often called a swamp cooler, pulls hot outdoor air through pads soaked with water. As the water evaporates, it absorbs heat and the air comes out cooler. A small pump keeps the pads wet and a large fan pushes the cooled air into the house.
According to the Department of Energy, this process can drop air temperature by 15 to 40 degrees. The cooler brings in a steady stream of fresh outdoor air, so you must leave some windows partly open. That gives warm indoor air a way out. The DOE suggests about 1 to 2 square feet of window opening for each 1,000 CFM of cooler capacity.
How a Central Air Conditioner Works
A central air conditioner uses refrigerant and a compressor to move heat from inside your home to the outdoor unit. It recirculates the same indoor air through a filter, with windows and doors closed. As it cools, it also pulls moisture out of the air, which drains away through the condensate line.
A heat pump works the same way in summer and can reverse to heat your home in winter. Our comparison of heat pumps and traditional AC explains the difference.
Evaporative Cooler vs AC: Side-by-Side Comparison
An evaporative cooler wins on cost. Central AC wins on comfort, control, and reliability in every season.
| Factor | Evaporative cooler | Central air conditioner |
|---|---|---|
| Installation cost | About half the cost of central AC | Higher upfront cost |
| Energy use | About one quarter of central AC | The largest electric load in most Phoenix homes |
| Water use | Uses water every hour it runs | None |
| Cooling power | Limited by outdoor humidity | Holds your set point in any weather |
| Monsoon performance | Drops sharply when dew points pass 55 | Unaffected, and removes moisture |
| Indoor humidity | Adds moisture | Removes moisture |
| Air supply | Constant fresh outdoor air | Filtered, recirculated indoor air |
| Dust | Can pull outdoor dust inside | Filter traps dust |
| Windows | Must stay partly open | Stay closed |
| Upkeep | Monthly checks, pads replaced at least twice a season | Filter changes and a yearly tune-up |
| Heating | None | Available with a heat pump |
Cost and energy figures come from the U.S. Department of Energy.
Operating Cost
The energy gap is real. A cooler runs a fan and a small pump, while an AC runs a compressor. But the savings shrink once you add water costs, replacement pads, and the months a cooler cannot keep up. Our breakdown of average summer cooling costs in Phoenix shows where AC dollars go and how to trim them.
Maintenance
Evaporative coolers need more hands-on care. The DOE recommends checking the pads, pump, and reservoir at least monthly in hot climates and replacing pads at least twice a season. Phoenix tap water is hard, so mineral scale builds up on pads and in the pan faster than in many places. Most coolers sit on the roof, which means ladder work and a risk of roof leaks.
Central AC needs regular filter changes and a yearly professional tune-up. Our AC maintenance tips cover what you can handle yourself.
The Monsoon Problem
An evaporative cooler only works when the air is dry enough to soak up more water. Phoenix monsoon season, which officially runs June 15 through September 30, is exactly when the air stops being dry.
Dew point is the best number to watch. It measures how much moisture is in the air, no matter the temperature. Phoenix forecasters long used a dew point of 55 degrees as the marker for monsoon conditions. A National Weather Service study of Sky Harbor data found afternoon dew points above 55 on nearly three out of four monsoon days.
As a general rule of thumb, here is how a typical cooler performs as dew points rise:
| Outdoor dew point | Typical cooler performance |
|---|---|
| Below 40 | Strong. Large temperature drop and comfortable air. |
| 40 to 55 | Fair to good. Smaller drop, slightly damp air. |
| Above 55 | Poor. Little cooling and a sticky, muggy house. |
Extreme heat adds a second problem. Even a strong 25 degree drop on a 115 degree day leaves air near 90 coming out of the vents. That may be fine for a garage, but it is not comfortable for a bedroom.
Central AC does not have this limit. It removes moisture as it cools, which is why it keeps working when monsoon storms roll in. Our post on why AC struggles in monsoon humidity explains what to expect from your AC during those weeks.
Which System Fits Your Home?
The right choice depends on how you live, who is in the house, and how much comfort you expect in July and August.
An Evaporative Cooler Makes Sense When
- You mainly need cooling in the dry months of April, May, early June, and October
- You are cooling a garage, workshop, or covered patio
- You are comfortable with indoor temperatures in the low to mid 80s
- You like fresh outdoor air and keeping windows open
- Lower upfront cost matters more than peak summer comfort
Central AC Is the Better Choice When
- You want a steady 75 to 78 degrees all summer, including monsoon weeks
- Someone in the home is older, very young, or has a health condition that makes heat risky
- Anyone has allergies or asthma, since a cooler pulls in outdoor dust and pollen
- You want windows closed for security or during haboobs
- You also want efficient winter heating from a heat pump
For most families living in their home year round, central AC is the safer main system. Phoenix summers are long and the monsoon months are some of the hardest.
Running Both: The Hybrid Approach
Many older Valley homes keep both systems. The cooler handles spring and fall when the air is dry, and the AC takes over once dew points climb. This can cut cooling costs during the shoulder months.
A few rules keep a hybrid setup working:
- Never run both at the same time. The cooler adds moisture that the AC then has to remove, so you pay twice.
- Close the cooler damper when the AC runs. If both share ductwork, moist cooler air reaching the AC coil can cause corrosion and mold.
- Winterize the cooler each fall. Drain it, shut off the water line, and cover or seal the opening so warm indoor air does not escape in winter.
- Watch the dew point, not the thermometer. Switch to AC once dew points stay above about 55.
Tip: If your cooler and AC share a duct system, have a technician confirm the damper actually seals. A leaking damper lets humid air into the AC side all summer.
Converting a Swamp Cooler to Refrigerated Air
Switching from a cooler to central AC is more than swapping one box for another. Plan for these steps.
- Check the ductwork. Cooler ducts are built to move large volumes of air and are often uninsulated or leaky. Many need sealing, resizing, or full replacement before they can carry AC. Our post on leaky ductwork in Phoenix covers the warning signs, and our team handles air duct replacement.
- Size the system correctly. A load calculation sets the right tonnage for your home. Guessing often leads to an oversized unit, as our post on why oversized AC units are common in Phoenix explains.
- Plan the electrical work. An AC condenser needs its own circuit, and older homes may need a panel upgrade.
- Remove the cooler and patch the roof. A roof cooler leaves an opening that must be sealed properly to prevent leaks.
- Consider ductless for homes without good ducts. A ductless mini split cools room by room without any ductwork.
New systems installed today use newer refrigerants such as R-454B or R-32, since new R-410A equipment can no longer be installed. SRP customers can still get Cool Cash rebates of $75 to $225 per ton on qualifying systems, while APS ended its equipment rebates on January 1, 2026. Our AC installation guide and our breakdown of AC cost for a 2,000 square foot home cover what to expect on price and process.
Frequently Asked Questions
Is a swamp cooler or AC cheaper to run in Phoenix?
A swamp cooler is cheaper to run. The Department of Energy says it uses about one quarter of the energy of central AC. Water, pad replacement, and its weak monsoon performance reduce those savings in practice.
Do swamp coolers work during monsoon season?
Not well. Once dew points rise above about 55 degrees, the air cannot absorb much more water, so the cooler adds moisture without much cooling. Many Phoenix homes with both systems switch to AC for July and August.
Can you run a swamp cooler and AC at the same time?
You should not. The cooler adds humidity that the AC must then remove, which wastes energy. If both share ductwork, close the cooler damper whenever the AC runs.
How much cooler can an evaporative cooler make my house?
An evaporative cooler can lower air temperature by 15 to 40 degrees in dry conditions, according to the DOE. On a humid day or a 115 degree afternoon, the indoor result can still be in the high 80s or warmer.
Do evaporative coolers bring dust into the house?
They can. A cooler pulls in a constant stream of outdoor air, which carries dust and pollen during haboobs and windy days. An add-on filter helps, but central AC with a good filter keeps far more dust out.
Is it worth converting a swamp cooler to AC in Phoenix?
For most full-time residents, yes. Central AC gives steady comfort through monsoon season and extreme heat, and a heat pump adds efficient winter heating. Ductwork condition is the biggest factor in the final cost.
Does an evaporative cooler use a lot of water?
Yes. It uses water every hour it runs, and use rises on the hottest, driest days. Central AC uses no water at your home.
Cooling Service in the Valley
Adams Refrigeration has served Phoenix since 1947, covering Glendale, Tolleson, Litchfield Park, Goodyear, Avondale, Buckeye, Peoria, Waddell, and Sun City. Our HVAC experts in Phoenix handle AC installation and repair, heat pumps, ductless mini splits, duct replacement, furnaces and gas heating, and indoor air quality.
We are a Carrier Factory Authorized Dealer, a Carrier President’s Award recipient, an Arizona Public Service Qualified Contractor, and a member of the Arizona Heat Pump Council, licensed under Arizona ROC 245268. Thinking about trading your swamp cooler for refrigerated air? Call (602) 269-6447 any hour and we will help you size the right system.