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Error four in the air conditioner indicates that the downward flow of air to the indoor unit is not working well. This could be caused by a clogged filter or something else.
In most cases, error 4 in the air conditioner is caused by a clogged filter. When you see error four on your device, you need to clean the filter outside the AC unit and wait for a few minutes before replacing it in its place and turning it back on again.
The best way to fix error 4 in the air conditioner is through cleaning when there's no power running through your AC unit, like during a blackout.
Error 4 in the air conditioner is a common problem when the AC unit cannot cool down the room.
When Error 4 occurs, it can be tricky to diagnose and fix because you might not know what exactly caused it. Many factors might cause this error - motor, thermostat, or another part in the HVAC (heating, ventilation and air conditioning) system.
In this article, I will cover how you should diagnose error 4 in an HVAC system if you want to avoid paying a visit to your local service center.
Error 4 in the air conditioner is a compressor malfunction. This is a symptom that can be seen in both split and single air conditioners.
Mostly, the repair of Error 4 in the air conditioner can be done by unplugging the compressor unit, removing the cover, assessing for any visible damage and reinstalling new parts.
The compressor should also be cleaned before being re-installed. The last step would be to ensure that the heat exchanger is free from corrosion and debris before it's reinstalled and plugged back into the power source when it's finished.
"Inspections, Installations, Repairs & Maintenance"
Metro Vancouver homes have specific requirements when it comes to central A/Cs, driven by climate, code, and the local housing stock. This page covers the essentials. Modern central A/C systems in Metro Vancouver run at 15-22 SEER2, with variable-speed inverter compressors that match output to load — eliminating the on/off cycling of older single-stage units.
BC's building code, TSBC gas-fitting rules, and FortisBC's natural-gas service standards together govern every HVAC installation in Metro Vancouver — CANRO works under permit and inspection on every gas-appliance install. CANRO has worked with central A/C systems across Metro Vancouver since 1999, including installations and service calls in Guildford, Maple Ridge, Guildford and Westwood Plateau.
Sizing. A/C sizing in Vancouver is typically 1 ton per 600-1,000 square feet depending on insulation, windows, and orientation. Over-sized A/C is the most common error — it leads to short-cycling, poor dehumidification, and premature compressor failure.
Lifespan. A properly maintained central A/C unit lasts 12-15 years. Vancouver's coastal salt air shortens outdoor-coil life — annual coil cleaning is more important here than inland.
Warning signs. A/C issues include warm air from supply registers, water leaks from the indoor coil (clogged condensate drain), refrigerant odour (R-410A leak), and noisy compressor startup.
Annual servicing in spring keeps the outdoor coil clean, the refrigerant charge correct, and the indoor evaporator coil and condensate drain clear. Skipping service is the single biggest cause of premature compressor failure.
A/C sizing in Vancouver is typically 1 ton (12,000 BTU) per 600-1,000 sq ft depending on insulation, windows, and orientation. Over-sized A/C is the most common error — it short-cycles, dehumidifies poorly, and shortens compressor life.
R-410A is being phased down (not phased out) under EPA AIM rules. Existing R-410A systems can continue to be serviced — refrigerant remains available for the foreseeable future, though prices may rise. New systems installed 2025+ increasingly use R-32 or R-454B with lower global-warming potential.
Indoor water leaks from central A/C indicate a clogged condensate drain (most common), a failed condensate pump on attic installs, a frozen evaporator coil thawing, or a damaged drain pan. All are repairable in a single service visit.
Vancouver summers have been getting hotter — the 2021 heat dome saw temperatures over 40°C. Most modern Vancouver homes now install a heat pump (heating + cooling in one) rather than a stand-alone A/C, taking advantage of rebates available for heat pumps but not stand-alone A/C.
A typical 2.5-3 ton central A/C added to an existing forced-air furnace costs $5,500-$9,500 installed. A heat-pump conversion (cooling + heating in one unit) is usually a smarter long-term investment given available rebates.
To book central A/C service or get a free written quote for installation, call CANRO at (604) 359-1081 or email info@canroheat.ca. We service all of Metro Vancouver including Guildford, Maple Ridge, Guildford and Westwood Plateau.
This guide was written by the CANRO Heating & Cooling team based on 25+ years of central A/C installation, repair and annual service work across Metro Vancouver. Last reviewed May 2026.
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