The $5,000 AC rule, explained
Multiply your air conditioner's age in years by the repair quote. If the result is more than $5,000, replacement is worth pricing. That is how This Old House states the rule, and it is a rule of thumb, not a standard.
Three worked examples
| System age | Repair quote | Age x cost | Rule says |
|---|---|---|---|
| 6 years | $300 capacitor | $1,800 | Repair |
| 12 years | $450 contactor | $5,400 | Price a replacement |
| 14 years | $2,200 compressor | $30,800 | Replace |
These are worked examples, not quotes. The repair amounts are within the national ranges published by Fixr and This Old House.
Where it falls short
The rule pushes you toward replacement for small repairs on older systems. The 12 year old system with a $450 part above crosses the line, but a cheap repair on a system that otherwise runs well is often still the right call, as long as you plan for a replacement. Use the rule to decide whether to get a replacement price, not to decide what to buy.
It also ignores things that matter in Tucson: whether the system keeps the house cool through a 78.9 day a year summer, whether the ducts leak into a hot attic, and whether you are paying for a repair every year.
A better version for Tucson
- Run the $5,000 test.
- If it fails, ask for a replacement quote alongside the repair quote.
- Compare the repair to the replacement price minus any TEP rebate (up to $600 for a high-efficiency AC or $720 for a heat pump through participating contractors).
- Consider timing. Replacing in spring is easier than in a July breakdown.
Questions Tucson homeowners ask
What is the $5,000 AC rule?
Multiply the system's age in years by the repair cost. If the result is more than $5,000, This Old House suggests you may need to replace it rather than repair it. It's a rule of thumb.
Does the $5,000 rule apply to heat pumps?
The same math works as a first check. Heat pumps run in both summer and winter, so they collect hours faster than an air conditioner of the same age.