R-Pro › Field cases › Air conditioning
Reduced Cooling Capacity — Unit runs but fails to cool adequately
Likely causes
Low refrigerant or refrigerant leak
Check: Connect manifold gauges — R-410A normal: low 7–8 bar, high 28–32 bar. Low below 5 bar confirms undercharge. Persistent bubbles in sight glass + frost on indoor suction line strongly suggests a leak. Scan flare joints at indoor unit, service valves at outdoor unit, and brazed joints with electronic leak detector; spray suspect joints with leak detection fluid
What to do: Repair the leak first (re-flare or re-braze) → recover all refrigerant → evacuate with vacuum pump to ≤500 micron for 30+ min → weigh-in exact nameplate charge. Do NOT top off without leak repair — will callback within months
Clogged air filter — reduced airflow from dust and debris
Check: Open front panel, remove filter, hold up to light — if light barely passes, heavily clogged. Measure discharge velocity with anemometer (typical wall-split 2.5–3.5 m/s normal; below 1.5 m/s = clogged). Also check return grille for dust buildup
What to do: Remove filter → vacuum off loose dust → wash with lukewarm water (≤40°C) and mild detergent → dry fully before reinstalling. Replace if torn/deformed. Clean monthly in dusty sites (factories/kitchens), every 2–3 months in homes. Clean return grille at the same time
Dirty evaporator coil — dust and oil film on fins
Check: Remove filter, shine LED flashlight on evaporator coil — clumped dust between fins or oil film (especially restaurants/smoking areas) indicates fouling. If airflow is normal but supply temp is above 12°C, suspect evaporator fouling. Check drain pan for odor/slime
What to do: Cut power → protect indoor casing/drain pan with plastic sheet → apply no-rinse coil cleaner → let dwell 15 min → rinse with low-pressure sprayer → clean drain pan and flush hose. For heavy fouling, pull-and-clean (use fin comb). Recommend 1–2 cleanings per year
Dirty condenser (outdoor unit) — poor heat rejection raises high pressure
Check: Visually inspect outdoor fins for dust, pollen, leaves, pet hair; high-side gauge rising (>35 bar on R-410A nearly confirms fouling). If outdoor discharge air feels lukewarm rather than hot, heat rejection is poor. Verify install location (discharge direction, wall clearance)
What to do: Cut power → remove casing → rinse fins top-down with water (pressure washer ≤20–30 bar, higher will bend fins). For heavy oil buildup, apply alkaline coil cleaner → 10 min dwell → rinse. Straighten bent fins with fin comb. Annual cleaning (spring) recommended
Compressor capacity loss — internal valve/piston wear
Check: Measure compressor running current — ±20% deviation from rating (e.g., rated 5A but reads ≤3A = capacity loss; ≥7A = overload). Read high/low gauges simultaneously — if compression ratio looks normal (e.g., R-410A summer 4.5–5) yet both pressures drift toward each other, suspect internal wear. Check crankcase oil level and color
What to do: Replace compressor — match model, refrigerant type, and capacity; recover refrigerant first. Always replace filter drier at the same time; evacuate to ≤500 micron for 30+ min; top up POE oil per manufacturer spec. If compressor was burnt out, flush the system before install. No field repair — replacement is the only option
Most common service call. 90% are solved just by cleaning the filter and outdoor unit. Before hooking up gauges, check the filter first — saves time; if dirty, clean and recheck after 30 min.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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