How Monsoon Season Humidity Impacts Your Air Conditioner

It’s that time of year again; monsoon season. You probably already know that Arizona’s summer monsoon season means more humidity in the air. But did you know your air conditioner must work harder to keep your home cool when the humidity is higher?

High humidity makes your home feel warmer, so you need to run your air conditioner more to keep it cool inside. You may lower the thermostat to stay cool, but that won’t increase your air conditioner’s ability to remove moisture from the air.

Lowering the thermostat will only make your A/C unit work harder, causing more equipment wear and tear and increasing your energy bills.

Signs of High Humidity in Your Home

Although Arizona doesn’t generally have the excessive humidity levels of other states, indoor humidity levels here can rise significantly during monsoon season.

When the indoor humidity level in your home rises above 50%, it allows mold and mildew growth and dust mites to thrive in the warm, humid environment. Decreased indoor air quality can lead to increased respiratory problems in your household.

Signs of excessive indoor humidity levels include foggy windows, a musty odor in rooms, and clammy skin.

Ideally, indoor humidity should never rise above 40%.

The Size of Your Air Conditioner is Crucial

The capacity of an air conditioner to cool a space is measured in British Thermal Units, or BTUs. The BTU number refers to the amount of heat the air conditioner can remove from the air in one hour.

A bigger air conditioner with more cooling capacity than your home needs is probably not the best air conditioner for your home, especially during our humid monsoon season.

If your air conditioner is too large for your home, the compressor will turn on and off more than it should, and the unit won’t run long enough in each cycle to remove an adequate amount of humidity from the air.

A too-large unit will also cost more to purchase, have higher operating costs, and experience more wear and tear on the system.

A unit that’s too small won’t keep your home cool enough, so having a correctly sized air conditioner is essential for optimum cooling.

Leaving the fan on when your air conditioner isn’t running to compensate may seem like it can provide some added cooling, but it can increase indoor humidity levels, as moisture may be drawn back into your home.

Your home’s floor plan, layout, ceiling height, and the number of stories all factor into the correct number of BTUs for your air conditioner.

As a general estimate of BTU requirements, a 1,500-2,000 square foot home needs an air conditioner with 30,000 BTUs, and a house of 2,000-2,400 square feet requires a unit with 34,000 BTUs.

A Chas Roberts HVAC pro can help you choose the best size A/C unit for your home.

SEER Ratings and Variable Speed Air Conditioners

SEER stands for Seasonal Energy Efficiency Ratio, and it’s used to measure an air conditioner’s efficiency and performance.

The higher the SEER, the less energy you’ll use for cooling your home.

Cooling systems are categorized by their SEER ratings:

  • Baseline efficiency: 13-16 SEER
  • Mid-efficiency: 16-18 SEER
  • High-efficiency: 20+ SEER

Air conditioners rated 16 SEER and above often have a two-stage compressor, allowing for longer run times. The longer run times of a two-stage compressor make it better at removing the humidity in your home.

Another benefit of 16 SEER and above units is that in addition to a two-stage compressor, they may also have two-speed condensing fans and blowers, adding to the benefits of the two-stage compressor.

Two-stage compressors can run at lower speeds, so these air conditioners are often quieter than units with single-speed compressors.

Higher SEER-rated air conditioners with two-stage compressors have a higher purchase price but can remove more humidity from the air and cost less to run than lower SEER units.

As of January 1, 2023, the minimum SEER rating required by the U.S. Department of Energy for new air conditioners sold in Arizona will rise to 15 from the current 14 SEER.

When it’s time to upgrade your current air conditioner, a 16+ SEER unit with a two-speed compressor is worth considering.

The Importance of Regular Air Conditioner Maintenance

Your air conditioner works harder than ever on the hot, humid days of the monsoon season, so it’s crucial not to neglect maintenance, or you may find you’re without air conditioning on the hottest days of summer.

Like any equipment, the better you maintain your air conditioner, the more efficiently it will run and the longer it will last. Regular A/C maintenance will help you avoid equipment breakdowns.

Chas Roberts has a 26-point maintenance plan to keep your A/C system in top condition. The cooling season checklist includes:

  • Check refrigerant levels
  • Inspect disconnect switch
  • Clean condenser coil
  • Test safety controls
  • Lubricate all moving parts
  • Check airflow
  • And more

Some manufacturer’s warranties require your air conditioner to be annually maintained to protect your warranty and keep the parts warranty current, which is another reason not to skip regular maintenance on your unit.

Aging Air Conditioners Run Less Efficiently

Air conditioners lose efficiency as they age, and the time will come when it’s best to replace an older unit.

After years of keeping your home cool during our brutally hot summers and humid monsoon seasons, higher energy bills and more frequent repairs may indicate that it’s time to replace your older air conditioner with a new, more efficient unit.

An older air conditioner may no longer be able to cope with the higher humidity of monsoon season.

According to the U.S. Department of Energy, even if your air conditioner is only ten years old, you may save 20-40% of your cooling energy costs with a new, more energy-efficient model.

A new higher SEER-rated air conditioner with a two-stage compressor is far more energy-efficient and can remove more humidity from the air than the older unit you may have now.

Chas Roberts can help you choose the right new air conditioner for your home to replace an aging unit.


Your air conditioner works hardest during the summer monsoon season, so you need to keep it professionally maintained to function well in the more humid conditions.

According to, air conditioning accounts for 12% of energy expenditures in U.S. homes, although it can be as high as 17% in the southwest.

Regular air conditioner maintenance and replacing an inefficient older unit will ensure your comfort at home throughout the summer monsoon season and beyond.

Chas Roberts is the oldest and largest HVAC provider in Arizona and has been family-owned and operated for over 75 years. Contact us for affordable, reliable service.