AC repair: what's wrong, what it costs, who to call

Most AC repair calls come down to a short list of problems: an airflow restriction, a failed electrical part in the outdoor unit, a clogged condensate drain, or a refrigerant leak. Start with the symptom you can see or hear, run the safe checks, and you will know whether you have a quick fix or a job for a licensed technician.

Updated November 2026 · General guidance, not an on-site diagnosis

Safety first. Turn the system off and call a pro if you smell burning, see smoke or sparks, or the breaker trips more than once. Never open the outdoor unit's electrical panel or handle refrigerant yourself.

How a central AC fails

A split-system central air conditioner has two halves. The outdoor unit holds the compressor, the condenser coil and a fan. The indoor unit holds the evaporator coil and the blower that pushes air through your ducts. Refrigerant circulates between them, picking up heat indoors and dumping it outside.

Almost every air conditioner repair falls into one of four groups:

Airflow problems. A clogged filter, blocked vents, a dirty coil or a weak blower. These cause poor cooling and frozen coils.
Electrical parts. Capacitors, contactors, fan motors and control boards. These cause a unit that hums, clicks or stays silent.
Water problems. A clogged condensate drain or a cracked drain pan. These cause leaks and safety-switch shutdowns.
Sealed-system problems. Refrigerant leaks and compressor failures. These are the expensive ones, and they are always a job for a licensed technician.

Start with the symptom

You do not need to name the broken part. You need to describe what the system is doing. It might be running and blowing warm air, silent, leaking, iced over, noisy, or tripping the breaker. Each of those points to a different short list of causes, and each has its own guide in this section with the checks that are safe to do yourself.

The safe homeowner checks are the same few every time: thermostat settings and batteries, breakers, the power switch at the furnace or air handler, the filter, supply and return vents, the condensate drain and pan, and debris around the outdoor unit. Anything behind a panel is outside that list.

What the repair will cost

The bill for central air repair has three parts: the diagnostic visit, the part, and the labor to reach and install it. Small electrical parts in the outdoor unit are the least expensive fixes. Coils and compressors are the most expensive because the refrigerant has to be recovered and recharged around the repair. The AC repair cost list by problem breaks this down part by part.

When a quote for a major part lands on an older system, the question changes from fixing it to whether fixing it still makes sense. The repair or replace calculator walks through that decision using your system's age, the repair size and its repair history.

Who to call

AC service belongs to a licensed HVAC contractor. Refrigerant work in particular is restricted by federal rule to technicians with EPA Section 608 certification. When you call, give the symptom, what you already checked, the age of the system and the model number from the outdoor unit's data plate. Ask what the diagnostic visit covers and whether that fee is credited toward the repair. A good technician shows you the failed part or the meter reading and gives you the price before starting work.

Common questions

Can I repair my air conditioner myself?

You can handle the basics: thermostat settings, breakers, filters, vents, the condensate drain and debris around the outdoor unit. Anything inside the electrical compartment or the refrigerant circuit is for a licensed technician. Capacitors hold a dangerous charge with the power off, and refrigerant handling requires EPA certification.

How do I choose an AC repair company near me?

Look for a state or local contractor license, proof of insurance, and a clear diagnostic fee quoted up front. Ask whether the technician will show you the failed part or test reading, and whether the repair carries a parts and labor warranty. Be cautious with a replacement recommendation that comes without a written diagnosis.

Is AC service the same as AC repair?

People use the terms loosely. Service usually means scheduled maintenance: cleaning, testing and catching weak parts before summer. Repair means fixing a specific fault after something has stopped working. A maintenance visit can turn into a repair if the technician finds a failing part, and you should get a price before that work starts.

Should I turn my AC off if it is not working right?

Yes in three cases: the coil or refrigerant line has ice on it, water is leaking near the indoor unit, or you hear loud buzzing, grinding or smell something burning. Running the system in those states can turn a small repair into a compressor or water-damage problem.

Sources

US EPA: Section 608 Technician Certification

What is it doing?

AC not blowing cold air?AC not blowing cold air: three safe checks to do now, the six most likely causes in order, what a technician will test, and when it points to replacement.AC running but not cooling the houseAC running but not cooling the house? Safe checks to do first, the likely causes in order, what a tech will measure, and when the system is simply too small.AC not turning on?AC not turning on? Work through the thermostat, breakers, power switch and drain safety switch, then see the likely causes and what a technician will test.Outside AC unit not runningOutside AC unit not turning on while the indoor fan runs? Safe checks, the likely causes from breaker to compressor, and what a technician will test.AC leaking water insideAC leaking water inside the house? Turn it off, check the drain line and pan, and see the likely causes, what a technician will do, and what you can clear.Frozen AC unit or evaporator coilAC unit frozen or ice on the evaporator coil? How to thaw it safely, the airflow and refrigerant causes behind it, and what a technician will check.AC refrigerant leakSigns of an AC refrigerant leak, what you can check safely, the repair options from leak fix to coil replacement, and what drives the cost of each.AC short cyclingAC short cycling? See the safe checks, the causes from dirty filters to an oversized system, what a technician will test, and when it means replacement.AC making noiseAC making loud noise? Match buzzing, humming, banging, hissing, squealing and rattling to their likely causes and learn which ones mean shut it off now.AC smells musty, burning, or like chemicalsAC smells musty, like burning, or like chemicals? What each odor points to, the safe checks, what a technician will clean or test, and when to shut it off.AC keeps tripping the breakerAC tripping the breaker? Reset it once, run the safe checks, and see the likely causes from a dirty coil to a shorted compressor and what a tech will test.Bad AC capacitorBad AC capacitor symptoms: humming outdoor unit, fan not spinning, hard starts and warm air. What you can check safely and how a technician tests the part.Bad AC compressorHow to tell if your AC compressor is bad: the symptoms, the cheaper faults that mimic it, the tests a technician runs, and your repair or replace options.

Services

Emergency AC repairWhat counts as an AC emergency, what to do in the first few minutes, what after-hours service involves, and the questions to ask before a tech is dispatched.AC tune-upWhat a proper AC tune up includes, what moves the price, how to prepare, what to ask, and how to tell a real maintenance visit from a sales call.Mini split repairMini split repair guide: why a ductless unit stops cooling, leaks water or flashes an error code, what you can check, and what drives the repair cost.

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