A well-tuned air conditioner is a quiet teammate. It starts, runs, and stops without fanfare, even on the hottest week of August. When it breaks, though, most homeowners learn more about HVAC parts in a single day than they wanted to know. After years in the trade, I’ve found that most service calls circle around a familiar group of components. Knowing what they do, how long they usually last, and what warning signs they give before failing can save money and stress. It also sharpens the conversation when you talk with HVAC companies or local HVAC contractors about repair versus replacement.

This guide walks through the most common AC repair parts, their real-world lifespans, why they fail, and how to think about maintenance or upgrades. I’ll focus on split central systems, but many lessons carry over to packaged units and heat pumps.

The compressor: the heart under pressure

The compressor moves refrigerant through the system, raising its pressure and temperature so heat can be released outdoors. Scroll and reciprocating compressors dominate residential systems. If the compressor dies, the “heart” stops pumping and the rest of the system sits idle.

Real-world lifespan

Typical range: 10 to 16 years. With ideal conditions and maintenance: 15 to 20 years is not unheard of. Early failures: within 5 to 8 years happen when installation is poor, refrigerant charge is off, or airflow is restricted.

Common failure modes Shorted windings from overheating, mechanical lockup, slugging from liquid refrigerant returning to the compressor, and loss of lubrication. I’ve opened systems where a clogged metering device starved the evaporator, superheat vanished, and the compressor took liquid on start up. It might run for months like that, then fail on a triple-digit day.

Warning signs Hard starting, brief humming then “click,” frequent breaker trips, or high head pressure readings. A seasoned tech will measure superheat/subcooling and check voltage drop and amp draw against nameplate RLA/FLA. If the numbers tell a story of chronic stress, the compressor’s on borrowed time.

Repair economics If the compressor is under parts warranty and the coil is in decent shape, replacement can make sense. Out of warranty, once labor, refrigerant, and dryer changes stack up, many homeowners choose a full system replacement, especially on equipment older than 10 to 12 years.

The contactor: a small part with big influence

A contactor is an electrically controlled switch that sends power to the outdoor unit. It’s one of the least expensive parts, yet accounts for a surprising number of no-cool calls.

Lifespan

5 to 10 years is typical. Coastal or dusty environments shorten it. Pitted contacts or an ant nest can kill it in a season.

Failure clues Intermittent outdoor unit operation, buzzing at the condenser, or a visibly stuck or burnt set of contacts. On maintenance visits, I check for carbon scoring and measure coil resistance. Swapping a contactor takes minutes and can add years of stable operation to older equipment.

Capacitors: cheap, silent workhorses

Start and run capacitors help motors come HVAC companies up to speed and stay efficient. When they go weak, motors draw more current and heat up. When they fail outright, you get a humming motor that won’t turn.

Lifespan

5 to 7 years for many off-the-shelf capacitors. Higher quality, oil-filled units can push past 10 years. Heat is the enemy. If the condenser bakes in full sun and airflow is marginal, the capacitor cooks.

Symptoms Fan blade or compressor tries to start, hums, then the thermal overload trips. A bulged top or leaking oil is the giveaway. With a meter that tests capacitance, we compare microfarads to the rating. Anything more than 6 to 10 percent off spec is a candidate for replacement.

A note on best practice When a capacitor fails, I also look for the why. Is the fan motor failing and overworking the capacitor? Is voltage sagging on startup? Replacing a 12‑dollar part without seeing the big picture can earn you another call in two weeks.

Condenser fan motor: a front-line component

The outdoor fan pulls air across the condenser coil, shedding heat from the refrigerant. If the fan is weak or dead, head pressure spikes and the compressor suffers.

Lifespan

8 to 12 years on average. Cheaper OEM motors and harsh climates can knock that down to 5 to 8 years.

Tell-tales Fan turns slowly, squeals, or stops entirely. The top of the unit feels hotter than usual. On gauges, head pressure climbs quickly. A high-pressure switch might trip and reset repeatedly. When I replace a fan motor, I match horsepower, RPM, frame size, and rotation, and I verify the blade pitch and diameter are correct. A mismatch can drop system efficiency and lead to repeat failures.

Blower motor: the indoor side of the airflow story

The indoor blower moves cooled air through the ductwork and across the evaporator. Older systems use PSC motors; newer ones often have ECM motors with variable speed.

Lifespan

PSC motors: 10 to 15 years, though they run hotter and are sensitive to poor airflow. ECM motors: 12 to 18 years if kept clean and dry, but when they fail, the electronics often drive the cost up.

What affects life Restricted filters, dirty evaporator coils, or undersized return ducts make any blower motor run hotter. I’ve seen brand-new motors fail within a year in homes where the filter was never changed and the return grille was undersized by 30 percent. Static pressure matters. Good HVAC contractors will measure it and correct duct issues rather than just throwing in another motor.

Thermostats: small brains, big impact

Modern thermostats range from basic digital units to smart, learning models. Their job seems simple, but they regulate cycles and protect compressors with time delays and staging.

Lifespan

7 to 15 years. Batteries die long before the electronics in many cases. Smart stats rely on clean low-voltage wiring and a steady common. Loose connections can mimic a failing control board.

Failure clues Erratic temperatures, short cycling, blank screens, or settings that don’t “stick.” Always confirm thermostat problems by checking voltages at the air handler and condenser. Replacing a thermostat rarely fixes a low-voltage short caused by a rubbed wire in the attic.

Control boards and defrost controls

In air handlers and heat pumps, the control board coordinates blower operation, compressor staging, and safety switches. Heat pumps also have a defrost board that runs the reversing valve and timed defrost cycles.

Lifespan

8 to 15 years, with failures often tied to surges, moisture, or vibration. Boards in damp crawlspaces are particularly vulnerable.

Signs of trouble Random system resets, blower running nonstop, condenser dead with 24 volts present, or error codes on the board’s LED. I carry a surge protector recommendation for homes with frequent thunderstorms. An inexpensive protection device can add years to boards and thermostats.

Refrigerant metering devices: TXV, EEV, and fixed orifices

The metering device controls refrigerant flow into the evaporator coil. Many residential units use a TXV (thermostatic expansion valve) or a fixed orifice like a piston. Higher-end systems may use electronic expansion valves.

Lifespan

TXV bodies can last 10 to 20 years, but the powerhead or internal parts may stick sooner, especially with contamination. Pistons have few moving parts and can last decades, but are sensitive to charge and load conditions.

Failure modes Restricted TXV from waxy oil breakdown, a stuck piston, or debris clogging the screen. Symptoms include low suction pressure, high superheat, and a frosted line set. On the flip side, a flooded evaporator and very low superheat can point to a TXV stuck open. Before replacing a TXV, I fix the root cause: moisture, dirty system oil, or incorrect charge.

Evaporator and condenser coils: heat exchangers that collect everything

Coils transfer heat. They also collect dust, pollen, cottonwood fluff, and kitchen grease. Over time, aluminum fins corrode, especially in coastal areas with salt exposure.

Lifespan

Evaporator coils: 10 to 15 years, often limited by corrosion or formicary (tiny) leaks. Condenser coils: 12 to 20 years with regular cleaning.

Telltale problems Gradual loss of capacity, ice on the evaporator, or the need to top off refrigerant annually. A coil that needs R‑22 or has widespread leaks may push you toward system replacement. When coils are cleaned yearly with appropriate chemicals and low-pressure water, head and suction pressures stay in the sweet spot and the compressor runs cooler.

Refrigerant lines and filter-driers

Line sets connect indoor and outdoor coils. Filter-driers live in the liquid line to catch moisture and debris.

Lifespan

Copper line sets: the life of the system if sized and installed correctly, but kinks or rub-throughs can cause leaks any time. Filter-driers: replace whenever the system is opened. They’re cheap insurance.

Clues Oil stains on lines, faint hissing, or UV dye at a flare fitting tell you refrigerant is escaping. Moisture in the system leads to acid formation, which attacks compressors and TXVs. On any major repair, I pull a deep vacuum to 500 microns or better, watch for decay, and replace the drier. Skipping that step is how you meet the same system again next summer.

Pressure switches and safety controls

High- and low-pressure switches protect the compressor from extreme conditions. Some units include discharge line temperature sensors and float switches for condensate overflow.

Lifespan

10 to 20 years, often outlasting the unit unless they cycle frequently from underlying problems.

What to watch for Nuisance trips that reset when the unit cools down point to airflow or charge issues, not a bad switch. A float switch that kills the system is doing its job. Find the clogged drain and slime buildup rather than bypassing the safety.

Condensate drains, pans, and pumps

Cooling wrings moisture from the air. That condensate must go somewhere. When drains clog or pumps fail, you get ceiling stains, musty odors, or a tripped float switch.

Lifespan

Gravity drains and pans: as long as the unit, if kept clean. Condensate pumps: 5 to 8 years, sometimes less in lint-heavy environments like closets with return air.

Maintenance notes I treat drains with appropriate cleaner and check slope. I’ve seen pumps wired on shared circuits with dehumidifiers, then starved for power. A simple independent outlet and annual cleaning spare you emergency calls.

The reversing valve: when the AC is also a heat pump

If you have a heat pump, the reversing valve changes refrigerant flow to provide heating in winter and cooling in summer.

Lifespan

10 to 15 years, often the life of the heat pump. Failures usually come from coil contamination or lack of lubrication, not the valve alone.

Symptoms Stuck between modes, loud whoosh but no temperature change, or heating when you asked for cooling. I always confirm with temperature splits and refrigerant readings before condemning a valve. Replacing one requires recovering refrigerant and skilled brazing, so labor dominates the cost.

Electrical wiring, breakers, and disconnects

Aging conductors, loose lugs, corroded disconnects, and tired breakers trigger phantom problems that mimic bad parts.

Lifespan

Conductors and disconnects: 15 to 25 years, highly dependent on moisture and sun exposure. Breakers: decades, but heat cycling and oversized loads wear them down.

Red flags Melted insulation near the contactor, a hot disconnect handle, or scorch marks at wire terminations. On every call, I torque-check lugs and look for aluminum wire runs with antioxidant paste. A $15 non-fused disconnect replacement can prevent a $300 capacitor and fan motor failure down the road.

How maintenance extends part life, in practice

You hear “change the filter” so often because it works. Beyond that, targeted maintenance pays off:

Annual coil cleaning keeps compressor head pressure in a healthy range, lowering motor and capacitor stress. Measuring and adjusting refrigerant charge by superheat/subcooling, not guesswork, prevents liquid slugging and overheating. Static pressure testing reveals duct problems that overheat blower motors and freeze coils. Electrical checks find weak capacitors before peak season. Replacing a 30/5 µF capacitor reading 24/3 avoids a 6 pm Saturday breakdown. Proper vacuum and drier replacement after any refrigerant-side opening stops acid formation that shortens compressor and TXV life.

These tasks separate thorough HVAC companies from parts-changers. A good maintenance visit feels like an inspection and tune, not just a filter swap.

Typical lifespans at a glance, and what skews them

Every home is a different ecosystem. Two identical units, same brand and model, can have ten-year gaps in lifespan because of installation quality and environment. I’ve seen desert installations with immaculate coil access panels, perfect charge, and shaded condensers run 18 summers without a major part. I’ve also pulled a three-year-old compressor out of a system on a third-floor balcony where the condenser baked in a windless corner and never got cleaned.

Factors that shorten life

High static pressure from undersized returns or restrictive filters. Refrigerant leaks and repeated recharging rather than repair. Dirty coils, especially in kitchens and near busy roads. Voltage issues, including long wire runs and marginal lugs. Coastal salt air, which accelerates fin and cabinet corrosion.

Factors that extend life

Proper sizing and a careful commissioning process at install. Genuine spring maintenance before cooling season. Shade for the condenser with unblocked airflow, not shrubs tight against the coil. Correct duct design and filtration that balances capture with airflow.

When to repair and when to replace

Homeowners often ask for a simple rule. There isn’t one, but I use a decision frame:

If the unit is under 10 years old and the failed part is a peripheral item like a capacitor, contactor, or fan motor, repair is a strong choice. If the compressor, evaporator coil, or control board fails on a 12 to 15-year-old system that still uses R‑22, replacement is usually wiser. If you are facing repeat failures driven by duct or electrical issues, invest in fixing the root cause along with the part. Good HVAC contractors will show you static pressure readings, thermal images, or voltage logs to make the case.

In my own home, a 13-year-old condenser lost its fan motor in late June. The compressor amps looked fine, coil was clean, and the charge was on point. I replaced the motor and capacitor, documented static pressure, and scheduled duct tweaks for fall. That repair bought four more quiet summers before a planned full upgrade to a higher-SEER heat pump.

Cost ranges and planning

Prices vary by region and brand, and this isn’t a quote, but real-world ranges help with planning:

Capacitors: low to modest, including labor. Higher for dual caps on proprietary mounts. Contactors: similar low-to-modest range. Condenser fan motors: moderate to higher depending on OEM versus universal, and whether blades need replacement. Blower motors: wide range. PSC motors sit in the moderate band; ECM motors can be significantly higher. Control boards and defrost boards: moderate to high, brand dependent. TXV replacement: moderate to high, mostly labor. Access matters. Evaporator coil: high, often pushing toward replacement if the system is older. Compressor: high. On older units, replacement can cost close to a new outdoor unit after refrigerant and labor.

Reputable heating and air companies will explain the parts and labor breakdown and compare options. If you feel rushed toward a full system sale for a simple part, get a second opinion from local HVAC companies with strong reviews.

How to talk with a contractor and get better outcomes

A little shared language helps. When you call for air conditioning repair, mention symptoms, not just the end result. “The outdoor unit hums for two seconds, then clicks off, and the fan doesn’t spin unless I push it with a stick,” points to a weak capacitor or fan motor. “Airflow feels normal but it runs constantly without cooling” can hint at a failed compressor or a refrigerant problem. Details cut diagnosis time and keep the visit focused.

Ask for:

Measured data: supply and return temperatures, static pressure, microfarads on capacitors, amp draws, and superheat/subcooling. A simple explanation of the failed part’s job and what caused it to fail. Options: OEM versus universal parts, repair now with root-cause fix later, or replace with efficiency gains.

Good HVAC contractors don’t mind these questions. The ones who do are often the ones who rely on hurried part swaps.

Edge cases the brochures don’t cover

New systems that short-cycle: Sometimes a brand-new AC fails parts early because the thermostat anticipates poorly, or the charge was set on a mild day without final verification in heat. I’ve revisited installs after the first 95-degree day to dial in charge and blower speed. That 30 minutes can add years to a compressor. Multi-family buildings: Shared electrical grounds or long line sets can cause voltage sags or oil return issues. Expect more attention to wiring and piping support from experienced techs. Attic air handlers: High heat bakes boards and ECM modules. Even simple radiant barriers, improved attic ventilation, or moving the unit to a conditioned closet has paid off in fewer failures. Variable-speed and inverter systems: Stunningly efficient, but parts are specialized. Lifespan can be excellent with clean power and careful commissioning. When they fail, diagnosis and parts sourcing take more finesse, and costs are higher. Choose installers certified on the brand.

Keeping an eye on the furnace side

Even if this is about cooling, most split systems share an air handler or furnace. A failing furnace control board or inducer motor can stop the blower, which will halt AC cooling too. During AC repair visits, I glance at the heat side: inducer bearings, igniter cracks, and heat exchanger condition. If you lump maintenance for AC and furnace repair together with the same company before peak seasons, you usually get better pricing and fewer surprises.

What a realistically “trouble-light” decade looks like

Here is how a typical homeowner’s AC might age if installed and maintained well:

Years 1 to 5: Few issues. Filters changed. Spring maintenance catches a slightly low dual capacitor in year 4, replaced proactively. Years 6 to 9: Condenser fan motor starts to whine in high heat in year 8. Replaced with a properly matched motor and blade, new capacitor fitted. Coil cleaning drops head pressure 20 to 40 psi under peak load. Thermostat firmware updated or replaced around year 7 if it acts glitchy. Years 10 to 12: A TXV becomes sluggish on muggy days. Suction pressure erratic. The system is still cool, but not crisp. A well-argued case is made to replace the TXV and drier, with a deep vacuum and oil analysis. From there, the compressor lives happily to year 14 or 15. At that point, current efficiency standards and refrigerant changes make a planned replacement more attractive than chasing leaks on an aging evaporator coil.

That arc isn’t guaranteed, but it’s common when a homeowner partners with a conscientious service team.

Final thoughts from the field

Air conditioners fail in patterns. The same five or six parts account for most calls: capacitors, contactors, fan motors, blower motors, thermostats, and, less frequently, compressors, coils, and TXVs. Lifespan isn’t a dice roll. It’s the sum of installation quality, operating environment, and maintenance. When you work with local HVAC companies that slow down long enough to measure, explain, and correct root causes, you spend less on emergency AC repair and more on predictable upkeep. And your home stays cool without drama, even when the thermometer looks like a dare.

If your system is acting up today, collect a few specifics before calling: any sounds you heard, how the fan behaved, the age of the unit, and whether filters were changed recently. Share that with the dispatcher. The right detail gets the right tech, the right part, and a faster fix.

Atlas Heating & Cooling

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What HVAC services does Atlas Heating & Cooling offer in Rock Hill, SC?

Atlas Heating & Cooling provides heating and air conditioning repairs, HVAC maintenance, and installation support for residential and commercial comfort needs in the Rock Hill area.

Where is Atlas Heating & Cooling located?

3290 India Hook Rd, Rock Hill, SC 29732 (Plus Code: XXXM+3G Rock Hill, South Carolina).

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Monday through Saturday, 7:30 AM to 6:30 PM. Closed Sunday.

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If you have a no-heat or no-cool issue, call (803) 839-0020 to discuss the problem and request the fastest available service options.

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Atlas Heating & Cooling serves Rock Hill and nearby communities (including York, Clover, Fort Mill, and nearby areas). For exact coverage, call (803) 839-0020 or visit https://atlasheatcool.com/.

How often should I schedule HVAC maintenance?

Many homeowners schedule maintenance twice per year—once before cooling season and once before heating season—to help reduce breakdowns and improve efficiency.

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