What a real air conditioning tune-up includes

Every spring the coupons arrive: a tune-up for a low, round number. Some are exactly what they say. Some are a technician standing in the yard for twenty minutes before recommending a new system. The difference is in what gets done, and you can tell from the invoice.

What a real one includes

• Measuring, not looking. A Pro with gauges and a thermometer checks the refrigerant charge by superheat or subcooling, the temperature drop across the indoor coil, the amperage of the compressor and the fan motors, and the capacitor values. Numbers go on the invoice.
• Cleaning the outdoor coil, properly, with the power off, a coil cleaner and a hose from the inside out. A coil packed with cottonwood fluff is the most common reason a system cannot keep up in July.
• Checking the indoor coil and the blower for dirt, and the condensate drain for a clog. A blocked drain is why an air conditioner leaks water on the ceiling below it in August.
• Checking the electrical connections, the contactor and the disconnect for burnt or loose terminals.
• Checking the thermostat and the ductwork for anything obvious: a disconnected run, a crushed flex duct, an open return in the attic.
• Testing static pressure, which tells the Pro whether the ducts are starving the system.

An hour, give or take. If the technician was there for twenty minutes and never opened the disconnect, that was a look, not a tune-up.

What you can do yourself

• Change the filter now and every one to three months through the summer.
• Clear two feet around the outdoor unit and hose it down gently from the top with the power off at the disconnect.
• Pour a cup of vinegar down the condensate drain line where it leaves the indoor unit, once a month in summer, to keep the algae from clogging it.
• Keep the supply and return grilles open and clear. Closing vents in unused rooms does not save money; it raises the pressure and stresses the system.

Refrigerant

A system that is low on refrigerant has a leak. Refrigerant does not get used up. A Pro who tops it off every spring and charges for the gas without finding the leak is selling you the same repair every year, and with the older refrigerants now expensive and being phased out, it is a costly habit. Ask them to find the leak and quote the fix, then decide.

When it is a sales call

A tune-up that ends with "this system is about done" may be honest; a fifteen-year-old system often is. Ask what they measured. Ask what would fail and when. Get the numbers, get a second opinion from another Pro who is not selling equipment that day, and see the heat pump piece in this section before you decide what to replace it with.

Maintenance plans

Most Pros sell a yearly plan with a spring and fall visit, priority service and a discount on repairs. They are worth it if the visits are real and if you would otherwise not schedule them. They are a way of paying for the reminder.