A common rule of thumb is the "5,000 rule": multiply the system's age (in years) by the repair cost. If the result exceeds $5,000, replacement is usually the better investment. For example, a 12-year-old system facing a $500 repair scores 6,000 — lean toward replacement.
Age alone is a strong signal. Most central air conditioners and heat pumps last 15–20 years; furnaces 20–30 years. If your system is within 5 years of that threshold and needs a significant repair, replacement economics almost always win.
Efficiency is the other factor. Older systems often run at 60–80% AFUE or 10–12 SEER. Modern equipment routinely hits 95%+ AFUE and 18–20 SEER. The energy savings on a new system can offset a meaningful portion of the installation cost over time.
If your system is under 10 years old and the repair is a single component — capacitor, contactor, reversing valve — repair almost always makes sense. Call DMES LLC for an honest assessment; we'll tell you what we'd do if it were our own home.
Information provided is general guidance for homeowners. Every home is different — contact DMES LLC for advice specific to your situation.