When your AC starts limping through summer—barely cooling, constantly breaking down, or driving up the electric bill—it’s tempting to patch it up and stretch one more season out of it. But the numbers tell a different story. Let’s take a hard look at the math behind replacing an aging AC system now versus waiting a few more years. Full chart comparison is at the bottom of the article.
Scenario: Old System, Frequent Repairs
Say your AC is 15–20 years old and costing you about $300 a year in repairs. That’s not unusual at this stage—capacitors, motors, refrigerant leaks, and other issues tend to pile up in systems past their prime.
Cost of repairs over 10 years:
$300 × 10 = $3,000
Now let’s say you ride it out for 5 more years, then finally replace it. With a 3% annual inflation rate, the $6,000 system you’re avoiding today will cost more later:
Future cost = $6,000 × (1.03)^5 ≈ $6,960
So your total cost becomes:
5 years of repairs + future system cost:
$1,500 (repairs) + $6,960 (install) = $8,460
If You Replace the System Today:
Upfront cost:$6,000
That’s a $2,460 difference just from avoiding five years of nickel-and-dime repairs and inflation.
Factoring in Efficiency Gains
Let’s add another layer to the decision: energy use.
If your current system is a 10 SEER, and you install a 14 SEER system, you’re looking at about a 28.5% efficiency jump. Let’s assume your current summer cooling costs run around $150/month, for 5 months a year. That’s $750 per season.
A 14 SEER system would drop your cooling costs by around 28.5%, saving you about:
$750 × 0.285 = $213.75/year
$214 × 10 years = $2,140
Now your $6,000 install starts looking even better:
$6,000 − $2,140 (energy savings) = $3,860 net cost after 10 years
The person who waits ends up here:
$1,500 (repairs) + $6,960 (install) − ~$1,400 (partial savings in later years) ≈ $7,060 net cost after 10 years
That’s $3,200 more over 10 years than the person who replaces their AC now.
Bottom Line:
Sticking with an old AC might feel like the conservative choice, but the numbers usually tell a different story. Between repair bills, rising system prices, and inefficient cooling costs, the longer you wait, the more you pay. Replacing now isn’t just about comfort—it’s a smarter long-term financial decision.
| Category | Replace Now (14 SEER) | Wait 5 Years |
|---|---|---|
| Upfront System Cost | $6,000 | $6,960* |
| Repair Costs (Years 1–5) | $0 (under warranty) | $1,500 |
| Repair Costs (Years 6–10) | $0 | $0 (new system under warranty) |
| Energy Savings Over 10 Years† | $2,140 | ~$1,400 |
| Total 10-Year Cost | $3,860 | $7,060 |
| 10-Year Cost Difference vs. Waiting | $3,200 savings | — |
†Compared to 10 SEER baseline, with $750/year average cooling cost over 5 months