Quick answer
A central AC replacement on existing ductwork takes 4 to 8 hours — one day for a two-person crew, with cooling running before they leave. A first-time install with a new line set, a new circuit and a condenser pad runs a full day or more, a furnace-and-AC swap 1–2 days, and a multi-zone ductless system 2–3 days. Recovering the old refrigerant and pulling a deep vacuum are part of every proper job.
How long air conditioner installation takes depends on what is already in the house. Replacing an existing central AC that is tied into working ductwork, with a line set that can be reused, is most of one day for a GTA crew. Everything that adds time — new copper through finished walls, a new circuit, a coil swap, a pad — is visible during the site visit, so a firm time window should come with the quote rather than as a surprise on the day.
Typical AC installation timelines by job type
- Straightforward central AC swap (existing ducts, reusable line set): 4–8 hours — the most common GTA scenario.
- First-time central AC with no prior cooling: a full day or more, for the new line set, electrical circuit and condenser pad.
- Furnace and AC replaced together: 1–2 days, though the bundle saves money — see replacing furnace and AC together.
- Ductless mini-split, single zone: about a day; multi-zone systems run 2–3 days for the extra heads and line sets.
What extends an AC install
- A new refrigerant line set — running fresh copper between the condenser and indoor coil adds hours, especially through finished walls or a floor.
- Line-set reuse questions — old copper can often be flushed and reused, but a kinked, undersized or buried line set gets replaced, and that decision belongs at the quote stage.
- Electrical work — a new disconnect, breaker or panel upgrade can mean coordinating an electrician into the same day.
- Evaporator coil replacement — an indoor coil that does not match the new outdoor unit has to be swapped, which means opening the plenum above the furnace.
- Old-unit removal and refrigerant recovery — recovering the charge into a cylinder rather than venting it takes time and is part of every legitimate install.
- Pouring or levelling a condenser pad, and awkward access: rooftops, tight side yards between semis, or a condo terrace.
What to expect on install day
- Arrival and protection — the crew lays floor coverings and confirms the equipment against the quote.
- Removal — the old condenser's refrigerant is recovered, the unit disconnected, and the indoor coil opened up.
- Set and connect — new condenser placed, line set brazed or connected, electrical and condensate tied in.
- Evacuation and charge — the system is pressure-tested, vacuumed down, charged by weight and leak-checked.
- Startup and walkthrough — temperature split verified, thermostat tested, and the crew shows you the filter and disconnect.
- Paperwork — model and serial recorded, the charge noted, and the AHRI match certificate left with you for warranty and rebate claims.
Why the vacuum step takes as long as it does
The stretch where the crew seems to be standing around is the part that decides the system's lifespan. After brazing — done with nitrogen flowing through the lines so scale cannot form inside the copper — the line set and coil are pulled down with a vacuum pump to remove air and moisture, verified with a micron gauge to around 500 microns, and held to prove the system is tight. Moisture left inside reacts with the oil and refrigerant into acid that eats the compressor over a few summers. A crew that skips the gauge and charges by pressure alone has cut the one corner that matters most.
Permits, licences and refrigerant rules in Ontario
The refrigerant side of the job must be handled by someone carrying an ODP (ozone depletion prevention) card, and the old charge has to be recovered, never vented. A new circuit or disconnect is electrical work under the ESA's rules, and some municipalities want an HVAC permit for a new condenser — the contractor arranges both. New systems now ship with R-32 or R-454B, mildly flammable A2L refrigerants with their own handling and equipment requirements; the A2L refrigerant guide explains what changes for a homeowner.
How to make install day go faster
- Clear a metre-wide path along the side of the house to the condenser location, and move anything stored in front of the furnace.
- Know where the electrical panel is and whether it has a free breaker slot or two.
- In a condo or townhouse, book the elevator or confirm truck parking ahead of time.
- Settle the thermostat location and Wi-Fi details before the crew arrives.
- Keep pets and kids away from the basement and side yard while brazing and recovery are underway.
Most GTA homeowners on a single-day swap are cooling the house by dinnertime. ZK Mechanical gives a firm window with every free AC installation quote after seeing the house — typical GTA install pricing is broken down separately — and booking the assessment online takes a minute.