Repair or replace your AC? A rule of thumb for New Orleans homes

The age times cost rule

Sears Home Services describes a simple rule of thumb: multiply the age of the system by the cost of the repair. If the answer is more than $5,000, replacing the system is usually the better value. A 12-year-old system facing a $500 repair scores 6,000, which leans toward replacement; a 6-year-old system with the same repair scores 3,000, which leans toward fixing it.

The same source puts the typical life of a central AC at 15 to 20 years. In our climate, where systems run from spring well into fall, long run hours and humidity are hard on equipment, and a well-kept system is far more likely to reach that range than a neglected one.

A few worked examples:

When the refrigerant decides for you

Systems installed before about 2010 may run on R-22, a refrigerant no longer used in new equipment and costly to buy. If an R-22 system needs a small electrical repair, fixing it can still make sense. If it has a refrigerant leak or a failed compressor, the cost of the refrigerant alone often tips the decision toward replacement.

The data plate on the outdoor unit names the refrigerant. If it says R-22 or HCFC-22, ask for the leak to be found and priced before anyone adds refrigerant, and ask for a replacement price alongside the repair.

Small repairs and big repairs

Not every repair counts the same. Capacitors, contactors, drain clogs and thermostat faults are cheap fixes that do not shorten a system's life; This Old House puts common AC repairs like these at about $150 to $650. Compressors, coils and leaks are another matter. HomeAdvisor puts a new compressor at about $800 to $2,800 and an evaporator coil at about $600 to $2,000, the kind of money that belongs in the age times cost math.

Warranty coverage changes the picture. A five-year-old system with a failed compressor may still have the part under the maker's warranty, which leaves labor and refrigerant. The serial number on the data plate tells a technician whether that applies.

What else should weigh on the decision

The math is a starting point. These signs push toward replacement even when the number is close:

• The system has needed several repairs in the last two years
• Rooms are uneven or the house stays humid even when it runs
• Electric bills have crept up with no change in how you use it
• The outdoor unit is rusted or its coil is badly damaged
• It runs on R-22 and has a refrigerant leak
• You are replacing ducts or adding rooms anyway
• The air handler and the outdoor unit are both past mid-life

Going the other way, a system under its parts warranty, a small electrical fault or a house you plan to sell soon all point toward repairing it.

If you replace, replace it right

Any new central AC installed in Louisiana must meet at least 14.3 SEER2, so even the basic option is a step up from an older system. Sears puts a central AC replacement at about $3,000 to $7,500 including installation. Entergy New Orleans customers have seen Energy Smart rebates of up to $500 on qualifying ENERGY STAR equipment, so check current terms before you buy.

The details decide how well a new system works: a load calculation instead of copying the old size, a coil matched to the outdoor unit, a clean or new line set, a deep vacuum and a charge by weight. Ask how each will be handled before you sign. Our AC replacement page covers what that looks like.

Sources

Figures in this guide come from these sources. Programs and prices change, so check current terms.

1. Sears Home Services: AC replacement cost and the age times cost rule
2. This Old House: air conditioner repair costs
3. HomeAdvisor: AC compressor repair and replacement costs
4. HomeAdvisor: evaporator coil replacement costs
5. Entergy: Energy Smart HVAC savings
6. askdoss: Louisiana HVAC installation costs and SEER2 minimums