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Cooling · MaintenanceAC Coil Cleaning
AC coil cleaning is a stand-alone deep clean of both coils: the outdoor condenser opened at the top and washed from the inside out, and the indoor evaporator reached through a panel in the plenum. Book it when a hose rinse has not brought the system back, when the coil ices with a clean filter, or after a heavy cottonwood season. A routine rinse is already part of a $120–$250 tune-up; this visit is for coils past that point.
A condenser coil gets rid of the heat the house gave up, and it can only do that through clean fins. Each June the cottonwoods along Halton's creek valleys shed fluff that the fan pulls flat against the coil, and lawn clippings, dryer lint and dandelion seed felt in behind it. The mat sits on the outside face but packs into the fins, so spraying from outside drives it deeper. The technician pulls the disconnect, lifts the top with the fan attached, and washes from the inside of the cabinet outward so the debris leaves the way it came in.
The evaporator coil sits in the plenum above the furnace and collects whatever the filter missed: drywall dust from a basement renovation, pet hair, kitchen grease. On an upflow furnace the dirt lands on the underside of the A-shaped coil, the face nobody sees from the access door. A matted evaporator cuts airflow, the coil temperature drops below freezing, and the coil ices over even though the refrigerant charge is correct. Cleaning it means opening the coil's access panel, or cutting and sealing one in the plenum where the coil was installed uncased.
Dirty coils show up in the readings before they show up as a breakdown. A blocked condenser raises head pressure, the compressor draws more amps and runs hotter, and every cycle runs longer to move the same heat. We record head pressure, compressor amp draw, the temperature drop across the indoor coil and the static pressure across it before cleaning, then again after. If the numbers do not move, the coil was not the problem and you hear that instead of getting a second invoice.
Units along the QEW and the 403 take road-salt spray all winter, and salt left on aluminum fins corrodes them; a spring wash clears it. Microchannel coils, the flat all-aluminum type on many newer condensers, are cleaned with low-pressure water and a neutral cleaner only, because strong alkaline or acid cleaners attack them. For a coil that just needs its yearly rinse, the AC tune-up covers it along with the charge and capacitor checks. Book a deep clean on its own through the contact page.
Signs a coil needs more than a rinse
- A grey felt of cottonwood fluff on the condenser that a garden hose did not shift
- The outdoor unit shuts off on the hottest afternoons and restarts once it has cooled
- Ice on the indoor coil or the large copper line with a fresh filter in place
- Weak airflow at every register after a renovation, with the filter and blower already checked
- Fins bent flat by a pressure washer, hail or a string trimmer, blocking part of the coil face
How it works
Describe the outdoor coil, whether the indoor coil has iced, and when the filter was last changed. If there is ice, switch cooling off and run the fan so the coil is thawed and testable when the technician arrives.
Pressures, amp draw, temperature drop and static pressure are recorded first. The condenser top comes off and the coil is washed from inside; the evaporator is cleaned through its panel, and the drain pan and trap are flushed afterward so loosened dirt does not block the drain.
The system runs a full cycle and the numbers are taken a second time and written on the invoice beside the first set. Bent fins are combed straight, the plenum panel is sealed with foil tape, and you get a note on how often your lot needs this.
Brands: Tube-and-fin and microchannel coils on Lennox, Carrier, Trane, Goodman, Rheem, Daikin, York, Amana and KeepRite systems are each cleaned by the method the manufacturer allows for that coil.
Common questions
Can I clean the condenser coil myself?
The outside rinse, yes: pull the disconnect, use a garden hose at gentle pressure, and never a pressure washer, which folds the fins flat. What a homeowner cannot do safely is lift the fan top and wash from the inside, and that is where a matted coil is cleared. Hosing off an AC condenser covers the safe version.
How often do AC coils need cleaning?
The condenser needs a rinse every spring and a deep wash when it mats, which on a lot near cottonwoods, a gravel lane or a dryer vent can be every year. The evaporator stays clean for many years behind a filter that fits and is changed on time. After a renovation, or a summer run with no filter, have it looked at.
Does a dirty coil damage the compressor?
Over time, yes. A blocked condenser coil cannot shed heat, so head pressure and compressor temperature rise and the motor draws more current for every hour it runs. A blocked evaporator can send liquid refrigerant back to the compressor, which is built to pump vapour only. Neither kills a compressor in a week; both shorten its life across several summers.
Does the evaporator coil have to be removed to clean it?
Rarely. Most coils are cleaned in place through the access panel with a brush, a vacuum and a cleaner that rinses into the drain pan. A coil matted solid on its underside sometimes has to come out, which means recovering the refrigerant and brazing it back in. On an older coil that is also leaking, evaporator coil replacement is the better use of that labour.
Will coil cleaning lower my hydro bill?
It lowers run time when the coil was the restriction, and the before-and-after readings show whether it was. We do not quote a percentage, because the saving depends on how blocked the coil was and how much the system runs. If the readings were normal before the wash, the bill will not change and the money is better spent elsewhere.