Phoenix Monsoon Season HVAC Checklist
Monsoon season (June–September) creates risks no other climate deals with: dust storms that pack condenser coils in a night, humidity spikes that overwhelm drainage, and power surges that kill control boards. This checklist covers what to do before, during, and after.
By Sorensen Heating & Cooling · April 2026 · 4 min read
Before Monsoon Season — Do These Now
Clear debris from around the outdoor condenser
Monsoon winds carry debris fast. Keep 2 feet of clearance on all sides. Trim any overhanging branches.
Clean or replace the air filter
Pre-monsoon is the right time — dust storms will overload a dirty filter and starve your system of airflow.
Check the condensate drain line
Monsoon humidity spikes mean your system generates far more condensate than normal. A clogged drain floods your ceiling or walls. Pour a cup of water in the drain pan — it should flow out within 60 seconds.
Inspect capacitors and contactors
These components hate heat and load spikes. If your unit is 5+ years old and hasn't been inspected — do it before monsoon season loads the grid.
Test your surge protector or install one
Monsoon lightning takes out HVAC control boards regularly. A $150 whole-home surge protector is cheap insurance against a $1,000+ board replacement.
Verify the disconnect box is properly sealed
The outdoor disconnect box should have no gaps, cracks, or missing covers. Monsoon rain gets in everything.
During & After Storms
Inspect the outdoor unit after major dust storms
Haboobs pack dust into condenser coils in one event. After a significant storm, rinse the coil with a garden hose if accessible. Professional cleaning if you had multiple storms.
Check for standing water around the condenser
The unit can handle light rain. But if it's sitting in standing water after flooding, shut it off and call us before restarting.
Listen for new sounds after storms
Debris in the condenser fan, contactor damage from power surges, capacitor degradation — all show up as new noises. Don't ignore them.
Watch for humidity complaints inside
If your home feels muggy during monsoon season even with the AC running, the system isn't keeping up with the latent load. This is often a sizing or airflow issue worth addressing.
Change the filter again after a significant haboob
One major dust storm can load a filter enough to drop airflow significantly. Don't wait for your normal replacement schedule.
The One Thing Most People Miss
The condensate drain line. During a normal Phoenix summer, your AC removes 1–3 gallons of moisture per hour. During a monsoon humidity spike, that can hit 4–5 gallons per hour. A partially clogged line that's “fine” all summer will back up and overflow within hours when the humidity spikes. The ceiling or wall damage that follows is $2,000–$8,000 depending on what gets wet. A $150 drain flush prevents all of it.
Want This Done Before Monsoon?
Our pre-monsoon tune-up covers every item on this list. Coil cleaning, capacitor check, drain flush, full system inspection.