Change your HVAC air filter
A plugged return filter is the first check when a San Diego AC feels weak, especially after a Santa Ana or a wildfire-smoke week.
What you'll learn
- What MERV rating is right for most San Diego homes (MERV 8–11)
- How to find your system's filter size (16×25×1 or 20×25×1 is typical)
- Why filter direction matters, arrows point toward the air handler
- When to swap (every 90 days, sooner with pets or wildfire smoke)
Step by step
- Turn the thermostat off (not the breaker).
- Find the return-air grille, wall, ceiling, or a slot at the furnace.
- Slide the old filter out. Note the arrow direction on the frame.
- Insert the new filter arrow pointing toward the furnace.
- Turn the thermostat back on.
If the filter is black, fuzzy, or wet, the system has been running under strain. Stop DIY and request a licensed company through Climate Pros SD. That company quotes its own visit. We do not install.
Rather have a pro handle it?
We match homeowners with licensed local HVAC pros across San Diego County. You reach us directly, not a national call center.
Keep learning.
Clear the condensate drain line
In San Diego humidity, condensate lines clog with algae by late summer. 5-minute job.
Program your thermostat efficiently
The U.S. Department of Energy says a programmable schedule can cut heating and cooling use about 10 percent when you actually use the setbacks.
Clean your outdoor condenser
A dusty or salt-crusted condenser makes the compressor work harder. Coastal San Diego units need a hose rinse more often than inland ones.