Air conditioning maintenance: what to know

What the job involves, what changes the price, and what to ask a pro.

What air conditioning maintenance is

Air conditioning maintenance is a seasonal service visit that cleans the coils, checks refrigerant and electrical parts, and clears the condensate drain so the system cools reliably. It is best booked before the cooling season starts.

Signs you need it

  • The system has not been serviced in about a year, or it has run since the last season without a visit.
  • The outdoor coil is dusty, matted with grass or cottonwood fluff, or has bent fins.
  • The indoor drain line shows algae, drips or standing water near the air handler.
  • The system runs longer on hot days than it did last summer.
  • The filter clogs within weeks, or the system gives off a musty smell when first started.
  • The house feels more humid than usual, even when the thermostat reaches the set temperature.

What the pro does

  • Shut off power and clean the outdoor condenser coil, and straighten bent fins as needed.
  • Clean the indoor evaporator coil and the drain pan, and check for mold or slime in the pan.
  • Clear and flush the condensate drain line, and test the float switch.
  • Measure refrigerant pressures, superheat or subcool, and check for a low charge or a restriction.
  • Test the capacitor and contactor, check the motor amp draw, and tighten electrical connections.
  • Check the blower and airflow, calibrate the thermostat, and run a full cooling cycle before leaving.

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Number of systems in the home, such as a main unit plus a second zone or a heat pump.
  • How dirty the outdoor coil is when the technician arrives.
  • Access to the outdoor unit and the indoor air handler, including attics, crawl spaces and tight closets.
  • Whether the visit includes a full refrigerant check or only a basic cleaning.
  • Whether the drain line needs more than a flush, such as a trap cleaning or a replacement section.
  • Failing parts found during the visit, such as a capacitor or contactor, and whether they are included in the visit.
  • Whether the home has a whole-home humidifier or air cleaner that also needs checking.

What a written quote should spell out

  • Each maintenance task listed, with coil cleaning, drain service and electrical checks named.
  • The refrigerant readings taken, and whether any refrigerant was added, with the amount and type.
  • Recommended parts or repairs, listed separately with the reason for each.
  • Whether the drain flush and float switch test are included.
  • The date of the next recommended service, and the readings recorded for your records.

Questions to ask before you hire

  • Will you clean both the outdoor coil and the indoor evaporator coil and drain pan?
  • Will you measure refrigerant pressures and tell me whether the charge is correct, or only top it off?
  • Which electrical parts do you test, and will you share the readings?
  • Will you clear the condensate drain and check the safety switch during this visit?
  • Will you check the outdoor fan motor and blades, and tell me if anything is bent or worn?
  • If you find a problem, will you call me before doing any work beyond the tune-up?
  • Will you give me a written summary with the readings?

Red flags

  • The visit does not clean the outdoor coil or check the indoor coil and drain pan.
  • The pro adds refrigerant without measuring pressures or finding out why the charge is low.
  • The pro pushes a replacement during a basic maintenance visit without readings to back it up.
  • The pro skips the drain line, then sells the drain service as an add-on repair.

What you can do yourself

After turning off the power, you can rinse dirt off the outside of the outdoor coil with a garden hose, and keep grass, leaves and debris clear of the unit. Do not remove the outdoor panel, touch the capacitor or work on refrigerant lines. Coil cleaning, drain service, pressure readings and electrical checks belong to a licensed technician.

Licenses and permits

Air conditioning maintenance is commonly done by licensed HVAC technicians, and refrigerant checks commonly require a certification. Check with your state or local licensing agency for the requirements that apply to service work in your area.

Air conditioning maintenance questions

When should I book AC maintenance?

Before the first hot stretch of the cooling season, so any fault can be found while the weather is mild. Booking in the middle of a heat wave takes longer.

Does maintenance mean I will not need repairs?

No. Maintenance finds wear early and cleans parts that cause strain, which lowers the odds of a failure in the middle of summer. It cannot prevent every failure.

What does the condensate drain do?

It carries away the water the indoor coil removes from the air. When it clogs, water can overflow, leak into the ceiling or trip the safety switch that shuts the system off.

Should I cover the outdoor unit in winter?

Not with a solid cover that traps moisture. Use a breathable cover or leave the unit uncovered, and keep snow clear of its sides.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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