Coil Cleaning in Houston, TX

What fouls an evaporator coil in a Houston attic

Pull the filter and look at the slot edges. Duct-board return plenums tear at the screw line. Air sneaks in around that tear. It never touches the filter. That bypass loads one corner of the coil first. You can see the pattern: a dark wedge, clean fins beside it. Tape fixes nothing. The rack needs rebuilding.

Blown-in fiberglass is the other feeder. Attic insulation migrates when someone walks the joists near the unit. Loose fibers land on the plenum seams. Then they ride through. Coils here come out furred, not dusty.

Humidity is why ours mat instead of brushing off. Fins stay wet through most of the year. Dust bonds to wet aluminum and sets. Slab coils in an upflow cabinet are worst, because you only reach one face. The entering side is the dirty side. Foam poured from the top misses it.

Check the P-trap before blaming the float switch. Houston condensate grows a brown slime that bridges the line. Secondary pans rust at the pooling corner. Ceiling stains show up below before anyone notices.

Some coils are not worth cleaning. Rust at the tube sheet. Fins flattened by a past service, aluminum already pitted. We will tell you that instead of selling a rinse.