Repair or replace your AC

Start with two numbers

How old is the system, and what does the repair cost? The data plate on the outdoor unit usually has the manufacture date, or the technician can read it from the serial number. This Old House puts the typical life of a home cooling system at 12 to 15 years.

• Capacitor, contactor, fan motor, thermostat, drain line. These are usually worth fixing on any system that otherwise runs well.
• Refrigerant leak. Worth fixing on a newer system if the leak can be found and repaired. On an old system that has leaked before, the next leak is coming.
• Compressor or evaporator coil. On a system over 12 years old, these often cost $1,000 to $3,000 and are the usual point where replacement wins.

The 5,000 rule, and its limits

A common rule of thumb multiplies the system's age by the repair cost. Over 5,000, replace; under, repair. A 14 year old system with a $400 repair scores 5,600, which says replace. I'd be careful with that. A $400 capacitor job on a system that otherwise runs fine is often the cheaper choice for several more summers. The rule is most useful for big repairs on old systems, where it agrees with common sense anyway.

Stockton specifics

• Age of the housing. About 44% of homes in our area were built before 1980, and the 1990s and 2000s subdivisions in Weston Ranch and Lathrop are now on their first or second system. A 2005 system is past 20.
• Refrigerant. Older R-22 systems are expensive to recharge because R-22 is no longer produced. A leaking R-22 system is a strong replacement candidate. R-410A systems can still be repaired with R-410A parts. The refrigerant change.
• Permits and testing. A replacement in California needs a permit and an independent test, which can turn up duct leaks that need fixing. Ask whether that is in the price. Permits and testing.
• The heat. Stockton now averages 29.2 days a year at 100°F or more. A system that struggled through 2024's 49 days is telling you something.

Days per year at 100°F or hotter, Stockton Metropolitan Airport

Questions to ask the technician

1. How old is the system, and what is its refrigerant?
2. What failed, and is anything else close to failing?
3. What does the repair cost, and what would a replacement cost?
4. If I repair it, what is the warranty on the part and the labor?