Repair or replace your AC? Reddit’s rules of thumb, fact-checked

Last updated: August 26, 2026

When an AC dies in an LA heat wave, the first stop is often Reddit, and the advice there is fast, confident, and contradictory. As a licensed HVAC contractor (CSLB #1031989 & #1055444), here's our honest read on the rules of thumb r/hvacadvice hands out every summer — which ones are sound engineering, and which ones are just tidy math.

Reddit claim: use the $5,000 rule — multiply the unit's age by the repair cost; over $5,000, replace

Verdict: Partly right. It's a decent sanity check and a terrible final answer. The rule correctly captures the idea that big repairs on old equipment are bad investments. But it knows nothing about the two things that actually drive the decision: what refrigerant the system uses (see below) and whether the failing part is covered by warranty. A $900 blower motor on a 12-year-old system "fails" the formula math differently than a $900 repair on a system whose compressor is still under a registered 10-year parts warranty. Use the rule to know when to start asking the replacement question — not to answer it.

Reddit claim: if it's an R-22 system, don't put another dollar into it

Verdict: Mostly right for major or refrigerant-circuit repairs, but too broad as an absolute. R-22 refrigerant was phased out of new US production and import in 2020, so repairs that require additional refrigerant rely on reclaimed or previously produced supply and can become expensive. On an aging R-22 system, a compressor, coil or significant refrigerant leak usually strengthens the case for replacement. A small non-refrigerant repair, such as a contactor or capacitor, can still make sense when the homeowner is deliberately buying time. The right comparison is the actual repair cost, remaining equipment condition, comfort performance and replacement plan.

Reddit claim: if the compressor dies, the whole unit is done

Verdict: It depends — mostly on warranty and age. A failed compressor on an aging, out-of-warranty system is usually the end; the repair is a large fraction of replacement cost, and the rest of the system has the same miles on it. But a compressor covered by a registered parts warranty changes the math substantially — you're paying labor, not the part. This is also where the industry's refrigerant transition matters: new equipment moved to new refrigerants (R-454B/R-32) starting in 2025, which affects parts logistics for older R-410A systems over time. A contractor should lay out both paths with real numbers for your system, not a forum's average one.

Reddit claim: the tech saying "replace it" is just selling — get a second opinion

Verdict: Partly right, and worth honoring. Reddit's skepticism has a real basis: some companies pay techs commission on replacements. The protection isn't cynicism, it's process. Ask for the diagnosis in writing (what part failed, refrigerant type, model/serial), ask for a repair-only quote alongside any replacement quote, and get a second opinion on any replacement recommendation over a few thousand dollars. A contractor confident in the diagnosis won't resist any of that. We'd rather lose a bid than win one on a diagnosis a homeowner couldn't verify.

Where Reddit can't help you

The repair-vs-replace call is really a planning call: if you replace, should it be a like-for-like AC or the moment you move to a heat pump? Does your panel have the capacity? Are the ducts worth keeping?

AC repair-vs-replacement checklist

• Diagnosis: get the failed component, refrigerant type, model and serial number in writing.
• Repair path: request the repair-only price, including refrigerant and labor if applicable.
• Warranty status: confirm registered parts coverage before assuming a major component must be purchased.
• System condition: consider age, coil condition, airflow, comfort problems and prior repair history together.
• Replacement path: compare like-for-like AC with heat-pump options and any duct or electrical work that would be required.

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FAQ

How long should a central AC last in LA?
Roughly 12–17 years is typical; coastal air, attic conditions, and maintenance history move it in both directions. Age alone isn't a verdict — it's one input.

Is it worth repairing a 15-year-old AC?
Usually only to buy time deliberately (e.g., a cheap repair while you plan a replacement on your schedule instead of during a heat wave). Large repairs at that age rarely pay back.

Should I replace the furnace and AC together?
Often yes if both are old — shared labor, matched components, one permit. And it's the natural moment to evaluate a heat pump, which replaces both.

Can I get a repair-only quote even if I probably need a replacement?
Yes, and you should ask for one. It's the cleanest way to see the trade side-by-side.

The claims above paraphrase recurring positions in public Reddit communities (r/hvacadvice, r/homeowners). No individual posts or users are quoted.

Related reading: Does HVAC brand matter? Reddit fact-check · Are heat pumps worth it in LA?