Coil Cleaning in Los Gatos, CA

What actually fouls a coil, and what we can check

Dirt reaches the coil two ways. Through the filter, or around it. Around it is the usual answer. Pull your filter and feel the downstream side of the rack. Gray felt on that lip means bypass air. A one-inch slot with no gasket leaks at every cycle. Duct board plenums shed fiber into the same stream. Add-on A-coils dropped over older furnaces sit in sheet metal that was never sealed.

Shine a flashlight at the coil face from below. Light should pass between the fins. A solid mat means the blower is already fighting. Check the secondary pan for a chalky tide line. That ring is proof of past overflow, not current health.

Chemistry matters more than people think. All-aluminum and microchannel coils do not tolerate strong alkaline cleaners. Residue left sitting in a steel pan etches it. We rinse, then rinse again, then confirm flow at the termination outside.

Access decides the day. Attic horizontals in vented spaces, closet uprights, crawlspace units on hangers. Each changes what has to come apart. Cased coils often mean cutting and resealing the plenum.

Rusted-through pans and crumbling fins end the conversation. Cleaning those is throwing good money after bad.