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Monsoon Season: How Arizona’s Humidity Affects Your Central AC

Monsoon season is here. Which means we’re about to get hit with uncomfortable humidity levels in the Valley.

But did you know that high humidity levels also add extra work for your air conditioner? And extra work means higher AC bills for all Arizona homeowners.

Let us explain...

Humidity means longer run times & higher AC bills

The more humidity in the air, the less cooling your AC can provide in a given time. Which means longer run times for your central AC.

An air conditioner actually has 2 main responsibilities. It has to:

  1. Cool the air
  2. Dehumidify the air

And your air conditioner relies on super cold refrigerant-filled coils to both cool and dry out the air. These coils, called “evaporator coils”, sit inside the indoor AC unit and absorb heat and moisture from the air inside your home.

Evaporator Coils

What evaporator coils look like.

But those cold coils have a limited amount of “cooling power”. And the more moisture the evaporator coils have to absorb out of the air, the less cooling power is left over for changing the temperature of the air.

Evap Coils

So because all that extra moisture in the air “hoards” the cooling power from your evaporator coils, your AC has to run even longer to lower the temperature of your home.

And, unfortunately, longer run times means more energy usage. Therefore, from July to September, you can expect to see a spike in your energy bills due to the increase in humidity.

But we know that you will want to keep your energy bills under control this season. So let’s look at how you can lend your AC (and wallet) a helping hand this monsoon season...

Tips to beat indoor humidity

1. Keep vents open (yes, even in unused rooms)

Air Vents

Keeping all vents in your home open prevents humid outside air from getting pulled into your home.

By closing the supply vents (vents that push out cold air), your AC is breathing in more air than it’s able to “exhale” out, resulting in what’s called “negative pressure” inside the house. And negative pressure causes humid outside air to get sucked into your home, raising the indoor humidity levels.

Increased humidity is just one downfall of closing vents. To learn more about why closing vents is overall a bad idea, check out our blog, “Why Closing Air Vents in Unused Rooms Damages Your Cooling/Heating System”.

2. Keep the fan setting on your thermostat set to AUTO

Keeping your thermostat fan set to AUTO (not ON) ensures that your AC actually dehumidifies your home’s air.

On vs Auto Thermostat

How? Well, remember how your evaporator coils absorb moisture from the air? Well, over time, condensation builds on the coils. And eventually, that condensation is supposed to drip off the coils and drain away outdoors. In fact, until the moisture drains outside, the air isn’t actually being “dehumidified”.

So what does that process have to do with your thermostat fan setting? Well, when your fan is set to ON, it runs constantly. Which means all that moisture on your evaporator coils gets blown back into your home before it can drain away.

When your fan is set to AUTO, however, the fan stops blowing in between cooling cycles. Which means all that moisture on your evaporator coils has time to slowly drip off the evaporator coils and drain away outside.

Related: ON vs AUTO: One of These Thermostat Settings Cost You Big Time

3. Check and change your filter every 2 weeks

Monsoon season brings with it intense storms that kick up a lot of dust. Now, the more dust in the air the faster your air filter will clog up. And a clogged filter limits the amount of air your AC can “breathe” in. Meaning your AC can’t remove as much moisture or heat from your home, leaving you sweaty and uncomfortable.

The solution? Check your filter every 2 weeks during monsoon season and change it as needed. Normally we suggest the typical HVAC system needs a filter change every 1-3 months but the extra dust during monsoon season may warrant more frequent filter changes.

Related: Has Your Air Conditioner’s Filter Betrayed You?

Other AC problems you may see during monsoon season

Other AC problems you may see during monsoon season

Just like monsoon storms can clog your air filter, they can also clog your AC’s condenser (the outside unit).

Dirty condenser coils

Dirty condenser coils.

And here’s why that’s a problem: Your condenser is responsible for collecting the heat from the air inside your home and dumping that heat outside.

But if the unit is clogged with dirt and debris from monsoon storms, it can’t effectively push that heat outside. This forces your AC to work harder and longer to cool down your home.

What to do:

Check your condenser coils after every storm. Can you see a layer of dirt or other debris covering your condenser coils (like in the pic above)? If so, hose the coils off using a gentle setting. If you can’t tell or see your condenser, give us a call to do a full tune-up cleaning of your unit and system.