Air conditioning repair: what to know

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

What air conditioning repair is

Air conditioning repair fixes a central or ductless cooling system that does not cool, short cycles, freezes up, leaks water or makes unusual noise. People usually call when the house stops cooling during a heat spell.

Signs you need it

  • The air from the vents is warm or only slightly cool, even with the system set to cool.
  • The outdoor unit does not start, hums without starting, or the fan runs while the compressor stays off.
  • The system turns on and off every few minutes.
  • Ice forms on the refrigerant line, the indoor coil or the air handler.
  • Water pools near the indoor unit, which often means the condensate drain is blocked.
  • The breaker trips when the unit starts, or the system makes grinding, squealing or clicking noises.

What the pro does

  • Check the thermostat, the outdoor disconnect and the breaker, and look at the capacitor and contactor for burning or swelling.
  • Measure voltage at the outdoor unit and the amp draw of the compressor and fan motor against the nameplate.
  • Read refrigerant pressures, superheat or subcool, to tell whether the system is low on charge or has a restriction.
  • If refrigerant is low, find the leak with an electronic detector or dye, repair it, and recharge to the nameplate as a certified technician.
  • Inspect the indoor evaporator coil for ice or dirt, and check the blower and the filter.
  • Clear the condensate drain and test the float switch, so the system shuts off before water spills.

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Every job is different, so we do not publish prices.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.

  • Which part failed. A capacitor or contactor is a smaller job than a compressor or evaporator coil.
  • Whether a leak has to be found and sealed before the system can be recharged.
  • The refrigerant type. Older systems use refrigerants that are harder to source and more costly to service.
  • The age of the system and whether the failed part is still made for it.
  • Access to the outdoor unit and the indoor air handler, including attics, crawl spaces and tight closets.
  • Whether the fault is in the thermostat, the wiring or the control board, which changes how long the diagnosis takes.

What a written quote should spell out

  • The failed part with its model number, and whether the replacement is new, refurbished or used.
  • The amount and type of refrigerant added or recovered, and the leak test method used.
  • Any leak repair, listed separately from the recharge.
  • Electrical parts such as capacitors and contactors, with their ratings.
  • Post-repair readings for pressures, temperatures and amp draw, and the warranty on parts and labor.

Questions to ask before you hire

  • If my system is low on refrigerant, will you find and repair the leak before you add more?
  • Which refrigerant does my system use, and is it still available for service?
  • Will you test the capacitor, contactor and amp draw, or only replace what looks damaged?
  • If the coil froze, what caused it, and will that cause be fixed?
  • Will you clear the condensate drain and check the float switch during this visit?
  • If the compressor has failed, will you explain the repair and the replacement options side by side?
  • Do you carry parts for my brand on the truck, or will I wait for a return visit?

Red flags

  • The pro adds refrigerant without finding or fixing the leak.
  • The pro recommends a full replacement before testing the capacitor, the contactor and the amp draw.
  • The pro will not show the pressure readings or the failed part.
  • The quote says refrigerant added without the amount, the type or the leak test method.

What you can do yourself

You can check the thermostat batteries and settings, replace a dirty filter, and clear leaves and debris from around the outdoor unit with the power off. Do not open the electrical panel of the unit or touch the capacitor, since it can hold a charge. Refrigerant work commonly requires a refrigerant handling certification, so leave recharging and leak repair to a certified technician.

Licenses and permits

Air conditioning repair is commonly done by licensed HVAC contractors, and refrigerant handling commonly requires a certification. Check with your state or local licensing agency for any additional requirements that apply to electrical or mechanical work.

Air conditioning repair questions

Why is my AC blowing warm air?

Common causes are low refrigerant from a leak, a failed capacitor or contactor, a dirty coil, or a clogged filter that freezes the coil. A technician measures pressures and the outdoor unit's electrical draw to tell them apart.

Is it safe to keep running an AC that has frozen up?

No. Turn off cooling at the thermostat and let the ice melt. Running a frozen system can damage the compressor and cause water leaks. Call for service once the coil has thawed.

Why does my AC short cycle?

Short cycling often comes from a weak capacitor, a failing contactor, a dirty filter, a control board fault, or a refrigerant charge that is too high or too low. Short cycling stresses the compressor, so have it checked.

Can I recharge my AC myself?

No. Handling refrigerant commonly requires a refrigerant handling certification. Adding refrigerant without finding the leak means you will need to add more later.

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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