Last reviewed: September 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards
Most air conditioner repairs come down to a short list: capacitors, contactors, fan motors, clogged drains, dirty coils and refrigerant leaks. A failed compressor is the repair that most often turns into a replacement.
No federal source measures what any of these repairs cost. What can be established is which symptom points at which part, and which of them an owner can check before paying for a visit.
Symptom to part
| Symptom | Usual suspects | Owner fixable |
|---|---|---|
| Nothing runs | Thermostat, breaker, outdoor disconnect, float switch tripped by a full drain | Thermostat, breaker, drain |
| Outdoor unit hums, fan does not turn | Capacitor, contactor, seized fan motor | No |
| Runs but blows warm | Low charge from a leak, compressor not starting, dirty outdoor coil | Clear debris from the outdoor coil only |
| Weak airflow | Filter, frozen evaporator coil, blower motor, duct restriction | Filter |
| Ice on lines or coil | Airflow restriction or low refrigerant | Filter; then turn off and call |
| Water leaking indoors | Clogged condensate drain, cracked pan, frozen coil thawing | Clearing an accessible drain line |
| Short cycling | Oversized unit, thermostat location, low charge | No |
For a structured triage, see AC running but not cooling.
The parts that fail most
- Capacitor. Starts and runs the compressor and fan motors. The most common single failure, and inexpensive. See what a capacitor does.
- Contactor. The switch that powers the outdoor unit. Contacts pit and stick with wear.
- Condenser fan motor. Bearings wear; without the fan, head pressure climbs and the compressor protects itself by shutting down.
- Condensate drain. Algae and debris block it; the float switch then shuts the system off, or water overflows.
- Coils. A dirty outdoor coil cannot reject heat; a dirty indoor coil restricts airflow and can freeze.
- Refrigerant leak. A sealed system does not consume refrigerant, so needing more always means a leak. See what a recharge really means.
A failed compressor, a leaking evaporator coil, or a second major refrigerant repair on an R-410A system tends to tip the decision. R-410A supply is being cut under the federal HFC phasedown, so the refrigerant part of a large repair on an older system gets more expensive over time; see refrigerant prices. Age alone is a weaker signal: 19.7% of air conditioned homes run main cooling equipment 15 years old or more, and much of it works.
What an owner should check first
- Thermostat: cooling mode, setpoint below room temperature, fan on auto, working batteries.
- Breaker and outdoor disconnect: reset a tripped breaker once only.
- Filter: a blocked filter causes weak airflow and frozen coils.
- Outdoor unit: clear leaves, grass and debris from around and against the coil, with power off.
- Condensate drain: if the system has shut off and the pan is full, the float switch is doing its job.
If the outdoor unit is humming without the fan turning, switch the system off at the thermostat before calling. A motor that keeps trying to start can overheat.
What repairs cost
No federal series measures residential air conditioning repair prices. Any range you find is a vendor survey or contractor estimate. Make quotes comparable by asking for part and labour separately, what failed and why, and, for any refrigerant work, what refrigerant the system uses and how many pounds were added. Our page on what HVAC repair costs are actually measured explains the gap.
Frequently asked questions
What is the most common air conditioner repair?
Capacitor replacement, followed by contactors, condenser fan motors and clogged condensate drains. All are wear or maintenance items rather than failures of the sealed refrigeration system, and all are far less expensive than compressor or coil repairs.
Is it worth repairing an old air conditioner?
Electrical parts and drains are usually worth repairing at any age. A failed compressor, a leaking coil, or repeated refrigerant repairs on an R-410A system are the repairs that most often justify replacement instead, because refrigerant supply is tightening under the federal phasedown.
Why is my AC running but not cooling?
The common causes are a dirty filter or frozen coil restricting airflow, a dirty outdoor coil, low refrigerant charge from a leak, or a capacitor or compressor fault. The filter and outdoor coil debris are owner-checkable; the rest need measurement by a technician.
How much does AC repair cost?
No federal source measures it, so any published range is a vendor survey or contractor estimate. Ask for part and labour separately, what failed and why, and for refrigerant work, which refrigerant and how many pounds.
Methodology and limitations
Component descriptions are general to residential split air conditioners. Household counts and equipment age are EIA RECS 2020 table HC7.1, the current vintage for equipment data.
- We publish no repair prices, because no federal series measures them.
- Equipment age bands cover all main cooling equipment, not central systems alone.
- Nothing here is a diagnosis of a specific system.
Sources
- US Energy Information Administration, Residential Energy Consumption Survey 2020, table HC7.1.
- Code of Federal Regulations, 40 CFR 84.7, HFC phasedown schedule.
The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.
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