You should seriously consider replacing your HVAC unit when it’s more than 15 years old and requiring frequent repairs, when repair costs are approaching or exceeding half the cost of a new system, when your energy bills have been climbing without explanation, or when the system can no longer keep your home comfortable during Colorado’s seasonal extremes. Age plus performance are the two most reliable indicators — either one alone is a yellow flag; together they almost always make replacement the smarter financial move.

Age and Efficiency: The 15-Year Rule

Most central air conditioners and heat pumps last 12 to 17 years with regular maintenance. Gas furnaces tend to last a bit longer — 18 to 25 years in many cases — but they also lose efficiency as they age. An AC unit from 2008 or earlier likely has a SEER rating of 10 or below. Modern minimum-efficiency equipment starts at SEER2 14.3 in Colorado (which maps to roughly SEER 15 under the old rating system), and high-efficiency units reach SEER2 18 or higher. That efficiency gap translates directly into monthly energy costs — an older 10 SEER unit can cost 40% more to operate than a modern 16 SEER replacement running the same hours.

The Repair-vs-Replace Calculation

A useful rule of thumb: multiply the age of the system (in years) by the cost of the repair. If that number exceeds the cost of a new system, replacement is generally the smarter investment. For example, a 12-year-old AC with a $600 compressor repair yields 12 × $600 = $7,200 — if a replacement system is $7,000 to $9,000, the math starts to favor replacement, especially since the repaired unit is still 12 years old and approaching end of life.

Also factor in refrigerant type. Systems using R-22 (Freon) refrigerant — common in units installed before 2010 — are expensive to service because R-22 production was phased out and remaining supply is costly. A refrigerant leak on an R-22 system is often the tipping point that makes replacement clearly more economical than repair.

Performance and Comfort as Replacement Signals

Even a system that hasn’t failed may be worth replacing if it consistently fails to keep your home comfortable. Signs include rooms that never reach the set temperature on hot days, uneven temperatures between floors, excessive humidity indoors during summer (a sign the AC isn’t running long enough to dehumidify properly), or a furnace that short-cycles (turns on and off rapidly) in cold weather. Colorado’s wide day-to-night temperature swings and intense high-altitude UV also put more wear on outdoor components than comparable systems in lower-elevation climates.

  • System is 15+ years old
  • Repair costs exceed $1,500 on a unit older than 10 years
  • Refrigerant type is R-22 and the system has a leak
  • Energy bills have increased 20% or more with no change in usage patterns
  • System can’t maintain setpoint on 90°F+ days or sub-10°F nights
  • Two or more significant repairs needed in the past two years

Taking Advantage of Rebates and Financing

Replacing an HVAC unit is a significant investment, but federal tax credits and Xcel Energy rebates available to Colorado homeowners can meaningfully offset the cost — particularly for high-efficiency systems and heat pumps. Done’s team can help you identify which equipment qualifies and provide a straightforward estimate. Financing is also available if you’d prefer to spread the cost over time.

If you’re not sure whether repair or replacement makes sense for your situation, an honest assessment from a Done technician will give you the information you need without pressure. Visit our AC replacement page to learn more about what’s involved, or explore heat pump options if you’re interested in a system that efficiently handles both heating and cooling in Colorado’s climate. Financing options are available for qualified homeowners.