This walk covers a central air conditioner replacement from the moment the power is cut to the first cool cycle. Use it as a checklist on the day. Each stage ends with something you can see, hear, or read on paper before the crew moves on.
Before the Crew Arrives
Get the scope in writing. It should name the outdoor unit, the indoor coil or air handler, the line set, and whether the existing ductwork and thermostat are staying. If anything is vague, settle it before the day, not in the driveway.
Clear the path. Move vehicles, bins, and stored items away from the outdoor unit and the indoor equipment closet. Tell the crew where the pets will be. Name who is home and who has the keys.
Shutoff and Removal
Watch the power go off at the outdoor disconnect and at the breaker. Do not open the refrigerant service ports or the sealed system yourself. Recovering the refrigerant is the technician's job, and it is done before the lines are cut.
Ask where the recovered refrigerant goes and get a note of how much was recovered. Ask who hauls the old unit and whether the pad is being reused. Walk the site with the technician before the old equipment leaves, so you can see what was removed and what stayed.
Setting the New Outdoor Unit
Check that the new unit sits level on its pad and that the pad is solid. Look at the clearance on each side and above. The equipment manual gives the minimum clearances. Ask the technician to point to the figure they used and check it against the unit in front of you.
Look at the line set path. The lines should be supported, free of kinks, and sealed where they pass through the wall. Check that the insulation covers the full run of the suction line.
The Indoor Side
Confirm the indoor coil or air handler is the match the outdoor unit requires. Look at the condensate drain. The drain line should slope away from the unit and discharge to a point you can see. Ask whether a safety switch or a secondary drain is fitted, and ask where it discharges.
Check the filter. The filter size on the unit label should match the filter slot, and the filter should be seated with the airflow arrow pointing the right way.
Electrical and Controls
Look at the disconnect and the breaker before the power returns. The breaker size should match the label on the outdoor unit. Ask the technician to show you the label and the wire size they used. Confirm the disconnect is within reach of the unit and can be shut off during a later service call.
Set the thermostat together with the technician. Ask how the fan is set, how the heat and cool stages are wired, and whether any setting from the old thermostat was carried over.
Evacuation and Charge
Ask the technician to pull a deep vacuum and hold it for a set time before refrigerant goes in. A vacuum that holds shows the sealed side is tight. Ask what they did and how long they held it.
The refrigerant charge should be set by a method the technician can name, such as superheat or subcooling measurements taken at the unit. The amount added should be written on the paperwork. Ask for that record.
The First Cool Cycle
Let the system run through a full cycle before the crew leaves. Listen for the outdoor fan and compressor. Go inside and feel the supply air at the register. It should feel clearly cooler than the air at the return. Check that water is draining at the condensate outlet and that the indoor unit is not dripping onto the floor.
Watch for short cycling or a unit that does not stay running. Tell the technician before they pack up, while they can still look at it.
What to Keep
Collect the install record, the commissioning sheet with the charge and vacuum notes, photos of the nameplates on both units, and the warranty paperwork, including any registration you were asked to complete. Store them together in one folder. Those papers are what you will need for any later claim or service visit, and they are the starting point for the next planning date.
The central air conditioner page on this site turns the install year into a planning date and lists what to check as the unit ages. Start there when you are ready to set the next date. Warranty terms vary by manufacturer and by contract, so read the papers in the folder rather than relying on memory.