AC Compressor Replacement vs Full System Replacement

Homeowners in Alpharetta call with one core question: fix the compressor or replace the entire AC system. The right answer depends on diagnostics, humidity control needs, refrigerant type, and the age of the equipment. The goal is stable cooling in North Georgia’s moisture, not a bandage that fails in August.

Start with diagnostics, not guesses

A technician should confirm the failure mode before any price talk. A compressor locked rotor, a grounded winding, or slugging from liquid refrigerant calls for different decisions than a contactor failure or low-voltage control fault. A full electrical megohm test, a clamp meter reading on start and run amps, and a refrigerant analysis set the baseline. In Alpharetta, high humidity can mask capacity loss. A static pressure reading, coil inspection, and wet-bulb measurements often reveal that the system is short cycling and not wringing moisture from the air.

On service calls in Windward and Crabapple, many failures trace to mismatched indoor and outdoor units after a past partial change-out. The system cools the thermostat quickly but leaves RH near 60 percent. That leads to clammy rooms, musty smells, and duct sweating in bonus rooms.

The compressor-only path

A compressor swap can make sense when the system is under 8 years old, the indoor coil is clean, and the lineset is sound. If the unit uses R-410A, parts are available and often under manufacturer warranty. The math works best if the air handler, coil, and thermostat support modern staging or modulation. This keeps dehumidification performance on track.

The limits show up fast in Alpharetta’s August air. A new fixed-speed compressor in an old 10–13 SEER system will still cycle hard during late afternoon storms. Indoor RH can sit above 55 percent even while temperature looks fine. Expect comfort gaps in large rooms with tall ceilings, common in Glen Abbey and White Columns.

Full system replacement: when it is the smarter spend

A full AC replacement solves multiple weak points at once. It matches a variable-speed or inverter-driven outdoor unit with a variable-speed indoor blower and a matched aluminum evaporator coil. The installer sizes the equipment using a Manual J load calculation, not the old “same tonnage as before” guess. This matters in homes near Avalon and Halcyon, where insulation and window packages vary by phase and builder.

North Georgia mornings can push 90 percent humidity with mild temperatures. An inverter drive ramps low and holds long cycles. That longer runtime at low capacity strips moisture without overshooting the setpoint. Rooms feel cooler at the same temperature because RH drops into the 45–50 percent range. The payoff shows up in primary suites over garages and glass-heavy living rooms that face the Big Creek Greenway.

R-22 refrigerant and the age factor

If the system uses R-22, replacement pressure is high. R-22 is obsolete and costly. A compressor swap on an R-22 unit risks future leaks, coil corrosion, and hard-to-source parts. Systems past 10–12 years often have reduced coil efficiency and worn blower motors. The repair may run 30 to 50 percent of a full replacement and still leave high utility bills. In 30005 and 30022, many original builder systems have hit this window.

SEER2 standards and Alpharetta codes

Georgia’s 2026 minimum for split systems is 14.3 SEER2. Most Alpharetta homeowners upgrade to 16–20 SEER2 to capture humidity control and lower bills. Moving from a 10 SEER legacy unit to a 16+ SEER2 system can trim cooling costs by roughly 30–40 percent, especially in larger estates near Country Club of the South. One Hour Heating & Air Conditioning handles permitting with the City of Alpharetta and Fulton County and installs secondary drain pans and float switches to protect ceilings in multi-story homes.

What a quality replacement includes

A complete job pairs equipment, airflow, and controls. A variable-speed compressor with inverter drive. A matched aluminum evaporator coil. A lineset flush or replacement when required. Proper charge verified by superheat and subcool targets under SEER2 test conditions. A sealed return plenum to cut attic infiltration. A smart thermostat from Nest or Ecobee to lock in staging logic and humidity setpoints. In high-risk attics, a secondary drain pan with a wet switch prevents water damage near finished spaces.

For tight lots and side yards near Avalon and North Point Mall, Daikin Fit side-discharge units run quiet and save space. For larger parcels in Milton and Cumming, Trane TruComfort or Carrier variable-speed systems deliver very steady temperatures room to room.

Humidity-driven failures and short cycling

Short cycling is common in Alpharetta’s mixed climate. An oversized condenser cools the thermostat fast, then shuts off before the coil stays cold long enough to condense moisture. RH stays high, and mold risk rises in closets and finished basements. Manual J sizing prevents this. The contractor models window SHGC, attic R-value, infiltration, and orientation. A 5-ton guess in Wills Park often becomes a right-sized 3.5 to 4 tons with a variable-speed blower. The home feels cooler and smells cleaner with fewer starts and stops.

Compressor replacement vs full system replacement: how to judge

Choose compressor-only when the system is newer than 8 years, uses R-410A, is properly sized, and indoor components are compatible with staged cooling. Expect less improvement in humidity and efficiency than a full upgrade. Choose full replacement when the system uses R-22, is 10–15 years old, short cycles, or has rising bills and frequent repairs. Expect better dehumidification, quieter operation, and lower kWh use. Rebates and credits help offset cost.

Brands, rebates, and credentials that matter

One Hour Heating & Air Conditioning installs Trane, Carrier, Lennox, Goodman, and Rheem. The team also specifies high-end options like Daikin Fit and Mitsubishi Electric for low-profile, quiet operation in high-density developments near Halcyon. As an authorized dealer, the company aligns equipment with manufacturer requirements for extended warranties and rebate eligibility.

The firm is a Licensed Conditioned Air Contractor, Class II, in Georgia. That license covers unlimited residential and commercial capacity. Technicians are NATE-certified. They help clients secure Georgia Power HEIP rebates, often up to $1,000 on qualifying upgrades, and verify eligibility for the 2026 Federal Tax Credit under Section 25C, up to $2,000 on qualifying heat pumps. Many homeowners in 30004 and 30005 use these incentives to step up to higher SEER2 or dual-fuel systems.

Heat pumps, dual fuel, and ductless options in Alpharetta

Air-source heat pumps save money in shoulder seasons in Roswell and Johns Creek. A high-HSPF2 unit handles most winter days, while a gas furnace stages on only during true cold snaps. That hybrid dual-fuel setup fits large homes in White Columns where operating cost control matters.

Ductless multi-splits help with bonus rooms, sunrooms, and third-floor spaces where new duct runs are intrusive. They deliver zone control and humidity management without tearing up finished ceilings.

The installation details that protect your investment

A careful install prevents callbacks and protects finishes in luxury homes. The crew pressure-tests with nitrogen, pulls a deep vacuum below 500 microns, and verifies dryness. They calibrate airflow to 350–400 CFM per ton based on latent load needs. In Alpharetta’s humidity, they often set a slightly lower CFM to extend coil contact time for better moisture removal. They level the pad, isolate vibrations, and route condensate with cleanouts and proper slope to avoid attic leaks over living areas.

Smart home integration for stable comfort

A smart thermostat helps manage staging and humidity. Ecobee or Nest can target dehumidification even without a whole-home dehumidifier by dropping fan speed or extending low-stage runtime. Homeowners near the Ameris Bank Amphitheatre who travel often appreciate alerts for high humidity, clogged drains, or filter reminders. Integrations with indoor air quality monitors add control over RH and VOCs.

Timelines, access, and local logistics

Most full AC replacements finish in one day. Larger projects with lineset replacement, electrical upgrades, or attic platform work can run into a second day. Crews that work regularly in Alpharetta know how to protect hardwood floors, stone entries, and elevator lobbies in townhomes near the Avalon Shopping District. They stage materials to avoid HOA violations and coordinate crane lifts when condensers sit on rear retaining walls.

The cost conversation framed by risk and return

A compressor-only repair is the lower upfront spend. The risk is future failures in an aging system and higher bills over the next summers. A full system replacement costs more on day one but reduces kWh use and service calls. In homes with large glass areas and open stairwells, the comfort gain from variable-speed control is often the deciding factor. Owners report better sleep, fewer hot-cold swings, and drier air during August thunderstorms.

AC Replacement Alpharetta, GA: neighborhoods and response

Dispatch proximity matters during heat waves. Crews based near Avalon and the Big Creek Greenway can reach 30004, 30005, 30009, and 30022 quickly. They service Milton, Johns Creek, Roswell, and parts of Forsyth County as well. Specialty retrofits in Windward and Crabapple respect architecture, attic access limits, and community rules.

FAQ for Alpharetta homeowners

Do you help with Georgia Power rebates? Yes. Advisors confirm qualifying models and submit the required documentation. Most clients see up to $1,000 on select upgrades.

How long does a full AC replacement take? Most homes are completed in one day. Complex lineset or electrical work can add a second day.

What is the 2026 SEER2 minimum in Georgia? The minimum for split systems is 14.3 SEER2. Many Alpharetta installs land in the 16–20 SEER2 range for better humidity control.

Can you match a new outdoor unit to my old coil? Mixing generations often reduces efficiency and comfort. It can also void warranties. A matched system performs better and lasts longer.

Will a variable-speed system fix my humidity issues? In most Alpharetta homes, yes. Proper sizing, low-stage runtime, and correct airflow reduce indoor RH to 45–50 percent in summer.

Ready for a data-backed recommendation?

If the compressor failed, a technician can compare a R-410A compressor swap against a full SEER2 upgrade with Manual J sizing. The proposal should show projected kWh savings, humidity targets, and available incentives. Homeowners considering AC Replacement in Alpharetta, GA can schedule a free in-home estimate. One Hour Heating & Air Conditioning provides options from Trane, Carrier, Lennox, Goodman, Rheem, and premium Daikin Fit, with 10-year workmanship coverage available. Ask about the $2,000 Federal Tax Credit on qualifying central air conditioning replacement heat pumps and Georgia Power rebates. The team serves Windward, Crabapple, Avalon, Halcyon, Glen Abbey, White Columns, Wills Park, and the 30004 and 30005 zip codes with rapid dispatch and code-compliant installs.