Old AC Unit on a Home Inspection: How to Decide What to Ask For

What an "old AC unit" finding on a home inspection actually means

When an inspector flags a central AC condenser as "past design life," they're reading two numbers off the data plate — manufacture date and refrigerant type — and comparing them against published lifespan averages. Most home inspectors visually verify operation, take a supply-vs-return temperature differential at the registers, look for visible corrosion or refrigerant-line damage, and recommend further evaluation when something seems off. They can't pull refrigerant pressures, can't open the sealed system, can't run an electrical amp draw, and aren't licensed to detect a refrigerant leak beyond what's visible. The hedge is honest, and it leaves you with the call.

Three things turn that hedge into useful information: the refrigerant generation (R-22, R-410A, or R-454B / R-32), the unit's age relative to the design-life band, and the supply-vs-return differential. The refrigerant generation matters more than most buyers expect, and it's the biggest fork in the decision tree on the AC side that doesn't exist on the old furnace side.

Read the data plate before the rest of the report

The data plate is a small metal sticker on the side of the outdoor condenser. Three pieces of information matter: manufacture date (sometimes encoded in the serial number), refrigerant type, and SEER (newer units show SEER2).

Match the refrigerant type to its generation:

• R-22 ("Freon," "R-22," or "Freon 22") — pre-2010 unit, end of life. EPA ended new production and import in 2020. Existing recovered or recycled R-22 remains legal for service, but the price tail is real — commonly $90–$250 per pound, with a residential five-ton system holding 10–20 pounds. A leaking R-22 unit is a write-off in most buyer-side math: refrigerant cost on top of leak repair on a system that's already a generation behind. R-22 can't be topped off with R-410A or R-454B; the line set and coil have to swap together.
• R-410A — installed roughly 2010 through 2024. Manufacturing of new R-410A equipment stopped after January 1, 2025 under EPA's 700 GWP limit. Contractors can still install pre-2025 R-410A inventory (the May 2026 EPA reconsideration removed the installation deadline), and parts and refrigerant availability remain normal. An R-410A unit isn't an end-of-life signal on refrigerant alone.
• R-454B or R-32 — the post-2025 residential standards. If the unit is this new, you're not reading this guide.

The refrigerant tier sets your floor for what's reasonable to ask. R-22 with a leak unlocks the full-replacement ask in a way an R-410A unit at the same age and condition doesn't.

The age band and the 65°F testing limit

For central AC, the manufacturer and ASHRAE design life sits around 12 to 15 years. Observed field service life often runs 15 to 25 years with regular maintenance, longer in dry climates and shorter in humid coastal markets where salt air shortens condenser life. The ENERGY STAR replacement-consideration trigger is 10 years — a point to start thinking about replacement, not a deadline. Heat pumps run a tighter band — historically 10 to 15 years, with modern air-source heat pumps reaching 15 to 20-plus. Mini-splits don't have a published lifespan figure from DOE or ENERGY STAR; inspector hedging on a mini-split is read against the general "10-plus years" replacement-consideration trigger rather than a specific design-life number.

A second piece matters for many buyers: if your inspection happened on a day below 65°F outdoor, the inspector likely did not run the AC at all. The InterNACHI Standards of Practice allow inspectors to skip operating equipment when "the exterior temperature is below 65° Fahrenheit, or when other circumstances are not conducive to safe operation or may damage the equipment." Running an AC compressor in cold weather can damage it, so the limit is a real protection. Most buyers don't learn about it until they read the report and feel exposed for the first hot weekend after closing.

A quick reading of where you land:

• Past design life, no findings, working today. A budget conversation. Credit ask or year-one budget item.
• Past design life, low delta-T at the registers, but operating. Specialist call, then credit.
• Past design life, R-22, low refrigerant or visible refrigerant-line damage. The cleanest full-replacement trigger you'll see.
• Could not be tested (winter or shoulder-season closing below 65°F outdoor). Home warranty risk transfer, sometimes paired with a credit anchored to refrigerant tier and age alone.

The five reasonable paths, ranked by how often they fit

Once you have the refrigerant tier, the age, the delta-T reading (or the note that the inspector couldn't test), and a read on the seller's posture, the choice usually picks itself.

1. Ask the seller to replace the AC before close

The rare path. Reasonable when one of three things is true: the refrigerant is R-22 and there's a confirmed leak or low charge; an HVAC specialist confirms a meaningful defect (failed compressor windings, a leaking evaporator coil, a line set that has to be replaced); or the inspector's delta-T at the registers is well below the 14–22°F ASHI working target on a hot inspection day.

Replacement requests on age alone — "the condenser is 22 years old, please replace it" — are the asks that get sellers up from the table. Even when replacement is on the menu, you usually don't want the seller picking the contractor, the SEER tier, and the refrigerant generation. Their incentive is the cheapest unit a licensed installer will warranty, on the fastest schedule. You'd rather have the cash and pick your own.

2. Ask for a prorated credit at closing

The most common reasonable ask. Frame it as shared cost inheritance: "This unit has used up most of its expected life on your watch; I'll inherit the replacement, and I'd like to share that cost." A unit at 18 of an expected 20 years has about 10% of its life remaining; a credit ask sized to that fraction of replacement cost is the negotiation you can actually win.

A few anchors for the math:

• Anchor to a real number. Replacement-cost bands for a complete central AC system (condenser plus matched air handler or coil, no ductwork) cluster in the mid four to mid five figures. Tonnage, ductwork condition, and SEER tier move the number. A specialist quote during contingency is the cleanest anchor.
• R-22 sits on its own line. A leaking R-22 unit doesn't get "repaired"; it gets replaced, because the line set and coil have to swap. Price the credit as a full system replacement, not a recharge.
• Stay inside the normal envelope. Total inspection asks in the 3–5% of purchase price range are the normal band. Asks past 10% get sellers to relist.
• Take cash, not seller-installed work. A closing credit puts brand, contractor, SEER tier, refrigerant generation, and timing under your control. Most loan programs cap how much seller credit can apply at closing; if your prorated ask runs into that cap, ask your loan officer whether a price reduction is the cleaner mechanism.

For the deeper version of this calculus, repairs vs. credit after a home inspection walks through the trade-offs.

3. Take a home warranty as risk transfer

The cleanest path when the inspector couldn't load-test the AC. A seller-paid home warranty covering the AC for the first year shifts the "did the system survive the winter?" risk from your year-one budget onto the warranty company. Forum threads about winter-closing AC anxiety reliably surface this as the community advice when the load-test gap is the main unknown.

The caveats are the difference between a working risk transfer and a paper one. Negotiate AC coverage specifically — a generic home warranty's AC coverage may have age caps, replacement caps that won't cover a full system at modern refrigerant tiers, or a flat per-claim cap below what an actual repair runs. Read the pre-existing condition exclusion carefully; a BiggerPockets post-closing story documents a buyer who took possession and found the previous owner's repairs were patches — a coil sprayed with sealant, taped PVC drains rerouted to flowerbeds — and the warranty refused the claim as pre-existing improper repair. Ask for written terms: a warranty endorsement that says "AC compressor and refrigerant covered up to $X, no age cap" is a different product than the generic warranty the seller's agent suggested.

A smaller credit plus an AC-specific warranty endorsement is often what a seller will agree to when full replacement isn't on the table.

4. Bring in an HVAC specialist before the contingency ends

The leverage move. A standard home inspection tests whether the AC runs and reads a supply-vs-return delta. It doesn't pull refrigerant pressures, doesn't do an electrical amp draw on the compressor, doesn't detect refrigerant leaks beyond visual, and doesn't open the sealed system to inspect the coil. When the inspector wrote "recommend evaluation by HVAC technician," they're telling you the report has gone as far as their license and tools allow.

A specialist visit during the contingency converts the hedge into a hard finding. The tech can pull refrigerant pressures, run a leak check on the lines and coils, do an electrical amp draw under load, inspect the evaporator coil, and produce a replacement quote you can use in negotiation. The visit cost typically falls in the low three figures — the cheapest contingency-window leverage you can buy. Ask specifically for refrigerant pressures, a leak-check report, a delta-T reading at the registers, and a quote scoped to a comparable SEER and refrigerant tier. For when to escalate beyond the inspector more broadly, see when to call a specialist after inspection.

5. Accept the AC as a year-one budget item

The most common honest answer. Plenty of "old but working" central AC units close every week without a credit, a replacement, or a specialist visit. The unit will run for another season or three; you'll replace it on your timeline, with the SEER tier you want, with the contractor you trust. This path fits when the unit is functional, there's no R-22 leak or delta-T failure, the seller is firm, and you have reserve to cover the replacement in year one or two. The 1–2% of purchase price annually rule of thumb for older-home maintenance and capital absorbs an AC replacement cleanly when it's planned.

Choosing this path on purpose is different from choosing it because you ran out of fight. Naming it as a deliberate path lets you stop spending negotiation capital on the AC and redirect it to items that matter more — roof, foundation, sewer, electrical panel — when those show up in the same report. For the multi-system version of that triage, see aging systems and end-of-life findings on a home inspection.

Summer vs. winter closing: how seasonality shifts your leverage

The closing month changes the negotiation more than buyers expect. A summer closing with the AC failing on the inspection day is the strongest posture; sellers in that spot fix or credit. A summer closing with the AC working but old is standard prorated-credit territory. Shoulder-season closings (March–April or October–November) are quietly the best timing for a specialist quote — HVAC contractors are off peak utilization, so the quote runs faster and cheaper than the same quote in July, and a buyer can land a credit that's tighter than the seller's mental model of "what an AC costs in summer."

A winter closing is the trap most buyers don't see coming. The 65°F testing limit kicks in, the inspector couldn't load-test the unit, and your leverage shifts toward the home warranty risk transfer or a credit anchored to refrigerant tier and age alone. Negotiate the warranty endorsement or the credit now, while there's still a contingency clock running, rather than waiting to find out in May. For the negotiation tactics across all four seasons, how to negotiate after a home inspection is the companion read.

The bundled ask: old furnace and old AC at the same time

A house with an old AC often has a furnace that's also seen better days. The HVAC system shares a footprint — same closet, same ductwork, same thermostat — and pairing replacements at the same time is usually the cleanest install. Forum threads on dual-old-system houses cluster around a bundled credit in the $7,000–$15,000-plus range depending on tonnage, AFUE tier, refrigerant generation, and ductwork condition. If your report flags both, ask for the bundled credit rather than two separate credits. The math is the same; the negotiation is cleaner because the seller sees one ask, not two. For the furnace side, see old furnace on a home inspection.

Common mistakes and myths

• "It's 15 years old, so it has to go." Past design life with no findings and a normal delta-T is a budget conversation, not a deal breaker. Service life commonly runs to 20–25 years with maintenance.
• "R-22 means the AC is illegal." Not for service. EPA stopped new production and import of R-22 in 2020; existing recovered or recycled R-22 is still legal to use on legacy units. What R-22 means is that a leak is expensive to fix and a replacement, not a recharge, is usually the right call when problems appear.
• "The seller filled the Freon, so it's repaired." A refrigerant top-off without a leak repair is a stopgap. The refrigerant will leak again at the same rate.
• "I can ask for the full replacement cost as a credit." A prorated ask anchored to remaining design life is the version that wins. Full-replacement asks on still-working units send sellers back to the listing.
• "My R-410A unit is already obsolete." Not in any meaningful way. Manufacturing of new R-410A equipment stopped January 1, 2025, but contractors can still install pre-2025 inventory, parts remain widely available, and a 2022 R-410A unit isn't "behind" the way a 2002 R-22 unit is.

For system-level HVAC depth, HVAC issues on a home inspection report is the companion read; inspection repair costs covers cost framing without fake precision.

If you're trying to sort an AC finding alongside a stack of other items in your report and figure out which ones are worth the negotiation fight, InspectionTriage organizes the report by priority, gives cost context without fake precision, and structures the conversation you'll need to have with your agent before the contingency closes. See what's worth negotiating — free