Buying a Home With AC: The Real Checklist

"We're signing the preliminary sale agreement in three weeks for a four-room flat in Saint-Mandé. The seller advertises 'reversible air conditioning throughout the apartment, recently installed'. There are three split units, one outdoor unit in the courtyard, and that's all I know. No invoice, no manual, no identifiable brand without climbing a stepladder. The estate agent tells me it's 'a bonus'. I want to know whether it's a bonus or a €7,000 bill two years from now."

We get this call more and more often — and it almost always comes too late, one or two weeks before signing. A reversible air conditioning system that is already in place is neither an added value nor a trap: it is a piece of technical equipment whose real worth depends on five or six pieces of information nobody thinks to ask for before the deed.

This article does not revisit the energy performance certificate (DPE) or building-association approvals, both already covered on this blog. It sets out the protocol for auditing an existing air conditioning system during a property sale in Paris and the Île-de-France region: what a buyer should insist on, what a seller would be wise to prepare, and how to put an honest price on a system taken over with the property.

Why air conditioning is the blind spot of property sales

In a sale file in the Paris region, everything is framed: energy performance certificate, asbestos, lead, electrical and gas inspections, Carrez floor area, minutes of the last three general meetings of the building association, the amount of service charges. Air conditioning, however, falls under no mandatory survey at all. There is no equivalent of the electrical inspection for an air-to-air heat pump.

The result: the equipment is dealt with verbally. "It works very well", "we've had it serviced", "it's a Daikin." Three sentences that commit nobody and say nothing about the only parameter that matters: how many years of use are left, and at what cost?

We regularly visit buyers three to six months after they move in, only to discover:

• machines from 2010–2013 running on R410A, technically at the end of their life, where the slightest leak triggers the repair-or-replace decision;
• an outdoor unit mounted on the façade or in the courtyard with no trace whatsoever of approval at a general meeting;
• refrigerant pipework running through a shared duct, sometimes without fire sealing;
• condensate discharged into a rainwater downpipe or, worse, dripping onto the balcony below;
• a "5-year manufacturer's warranty" invoked by the seller, but non-transferable for lack of an invoice in their name and a registered commissioning.

None of these points blocks a sale. All of them can be priced, and all of them can be negotiated — provided they are known before signing.

The 9 points to check before you sign

1. The real age of the units, not the declared age

The rating plate on the outdoor unit carries a serial number and, with most manufacturers, a production date or week. It is the only non-negotiable piece of data. A seller may sincerely believe that "the AC is 5 years old" because they bought the property 5 years ago: the unit itself may well have been installed in 2011.

A realistic order of magnitude for a properly maintained residential wall-mounted split: 12 to 15 years of service life, sometimes 18 for high-end equipment under light use. Beyond 10 years, the buyer should think like someone buying a used car: the equipment works, but its trade-in value is low.

2. The refrigerant: R410A or R32

This is the single most decisive piece of information. It appears in plain text on the outdoor unit's plate ("Refrigerant: R410A, 1.45 kg").

Refrigerant	Typical installation period	What it means when buying
R22	before 2004	Banned from recharging since 2015. Equipment to be replaced, full stop.
R410A	2004 → 2018/2020	Still rechargeable, but being progressively phased out under the F-Gas Regulation. Price per kilo rising steadily.
R32	since 2018–2020	The current residential standard. Parts and refrigerant widely available.
R290 (propane)	marginal in splits, growing	Recent technology, very low climate impact.

An R410A installation is not doomed: it simply has no trade-in value. The right attitude for a buyer is to treat it as free comfort for 3 to 6 years, not as new equipment. We go through the decision in detail in our article on choosing between repairing or replacing an air conditioner over 10 years old.

3. Building-association approvals

This is the point that costs the most — and the easiest to check. In the minutes of the last three general meetings handed over by the notary, look for a resolution mentioning the installation, the fitting of an outdoor unit, or the name of the selling co-owner. If the installation is more than three years old, explicitly ask the seller or the managing agent in writing for the minutes of the general meeting that approved it.

Two scenarios:

• Approval voted and recorded: the equipment is in order, and the buyer inherits a right of private use. Perfect.
• No trace at all: the installation amounts to appropriating common property. Action for removal is time-barred after ten years (Article 42 of the Act of 10 July 1965), but it is the new owner, not the seller, who inherits the potential dispute. In a small building association, this is often settled by a regularisation resolution at the next general meeting — the approach described in our article on decision-making in a small building association with no professional managing agent.

4. The unit's service log

Above a 2 kg charge (roughly 5 kW of cooling capacity, so most multi-split and ducted systems), regulations require a periodic leak-tightness check by an operator holding a certificate of competence, with an intervention sheet issued (Articles R.543-75 et seq. of the French Environment Code). If the seller cannot produce a single sheet for an 8 kW multi-split, it means one simple thing: the unit has never been checked.

For a 2.5 kW single-split, there is no leak-tightness check requirement. Ask for the servicing invoices anyway: an 8-year-old air conditioner that has never been cleaned announces itself by smell long before it shows up on paper, and our article on musty smells and disinfection explains why.

5. Condensate drainage

During the viewing, find out where the water goes. Three sound configurations: gravity drainage into a wastewater downpipe with a trap, a condensate pump with a level safety switch, or a controlled outdoor discharge. One problematic configuration: a flexible hose poking out of the wall and dripping into thin air.

This is the leading cause of damage we see in apartments. Ask whether there has already been a water damage claim — and check the general meeting minutes, claims show up there.

6. The condition of the pipework and mountings

From outside, and from the courtyard if possible:

• is the refrigerant pipework insulated and sheathed, or bare and cracked by UV exposure?
• is the outdoor unit on anti-vibration mounts, or screwed straight into the wall shared with a neighbour's bedroom?
• are there signs of rust, oil seepage, persistent frost?

A simple indoor thermometer and hygrometer left in each room for 20 minutes during the viewing will already tell you whether the splits genuinely cool or heat the whole flat, or only the room they are installed in.

7. Remote controls, manuals and codes

A trivial detail with a real cost. A lost original remote control means €30 to €80; a proprietary Wi-Fi module that has not been reset stays paired to the seller's account; a missing manual means an hour of searching for every error code. Insist, at the handover inventory, on: all the remote controls, the printed manuals, and the disconnection of manufacturer accounts.

If the seller no longer has the manuals, the exact reference of the indoor unit (read off the side label) is usually enough to find them on the manufacturer's website. A small insulated multi-bit screwdriver and a head torch make reading it off far easier when the label sits behind the front panel.