R-Pro › Field cases › Air conditioning
AC Weak Cooling — Filter Clog (Most Common Cause)
Likely causes
Step 1 — Visual filter check and airflow measurement
Check: Filter color: white/light gray when new → yellow/black thick dust = clogged. Measure airflow (anemometer or hand) — below 50% of normal confirms clog. Frost on evaporator coil = result of filter clog (prolonged low airflow → coil surface below 0°C).
What to do: Remove filter → check for yellow/black dust. Measure airflow with anemometer or palm (below 50% of normal = clog confirmed). Inspect evaporator for frost — filter clog progresses to coil frosting. Confirm clog, then proceed to clean/replace step.
Step 2 — Clean or replace filter (every 3 months)
Check: Reusable filter (residential standard) = warm water + neutral detergent → fully dry → reinstall. Disposable HEPA/high-efficiency filters = replace. Recommended interval: residential 3 months, commercial/dusty environments 1 month. Educate user on schedule + set reminder.
What to do: After cleaning, run system 30 min → measure discharge temp (normal: 8–12°C delta between intake and discharge). Frosted coil = clean filter + OFF system, allow natural defrost (no dryer/direct heat = coil damage). After defrost, verify normal operation.
Filter check = user-doable before paid service call. Educate user: check before season + monthly. Pet households (cat/dog) = 2-month interval. For PM2.5 fine dust, recommend HEPA H13.
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