Repairs · Read 8 min
AC unit leaking water: causes and fixes
By the Aircadia team
In 8 cases out of 10, an AC unit leaking water indoors is releasing plain condensate — water produced by cooling the air — because of a full tray, a clogged drain hose or a dirty filter. That kind of leak often takes 20 minutes to fix. A refrigerant leak, by contrast, is rare but serious: recharging without first repairing it is illegal under the European F-Gas regulation.
Key points
- An AC dripping indoors = almost always condensate (harmless), not refrigerant (rare and serious).
- 3 causes cover 80 % of cases: full tray, clogged drain hose, dirty filter.
- Expect €150 to €250 for a repair in Nice on harmless leaks, €350 to €700 if a condensate pump has to be replaced.
- In case of a refrigerant leak, EU Regulation No 517/2014 “F-Gas” forbids any recharge before repair.
Where does the water dripping from an AC unit come from?
In cooling mode, the indoor unit chills a coil (the evaporator) below the dew point of the room air. Air moisture then condenses on the fins, exactly like the mist on a cold glass in summer. In Nice, where relative humidity often tops 70 % from May to September, a 3.5 kW split typically produces 0.5 to 1.5 litres of water per hour of operation.
That water — the condensate — falls into a tray below the evaporator, then flows by gravity or by a lift pump to the outside, through a PVC pipe or a soft tube. The circuit is sealed and invisible as long as everything works. The moment one link fails, water escapes at the lowest point: the front of the unit, a joint, or worse, the ceiling below.
Is it dangerous? Condensate or refrigerant?
That is the first question to settle, because it changes everything: severity, price, urgency, legal duties.
- Condensate (clear, odourless water, no greasy trace): harmless. No chemical whatsoever, just distilled water. The priority is to protect finishes (plaster, wood floors, furniture) while you repair.
- Refrigerant (oil traces, hissing, drop in cooling power): serious. The fluid (R32 on recent models, R410A before 2023) circulates under pressure in a sealed circuit. A leak rarely shows up as a puddle: more often as a sudden drop in cold air, frost on the copper pipes, or a hissing sound. An oil mark at the fittings is the most reliable clue.
Common myth to bust: “my AC drips, we need to recharge the gas”. No. A water leak is never related to the refrigerant. Many owners get sold a needless recharge (€200 to €400) when the issue was simply a blocked tray at €0. A serious professional always checks the condensate circuit first before any other hypothesis.
What are the 6 causes of an AC leaking water indoors?
Here are the causes ranked by frequency, with the typical diagnosis, DIY feasibility and the indicative price in Nice if you call a professional.
| # | Cause | Typical symptom | DIY? | Pro price in Nice |
|---|---|---|---|---|
| 1 | Clogged drain hose | Steady drip on the façade | Yes (blow / snake) | €150 – 200 |
| 2 | Fouled condensate tray (algae, dust) | Irregular flow after a hot summer | Yes (cover off + clean) | €180 – 250 |
| 3 | Very dirty air filter, ice on evaporator | Big intermittent drops, poor cooling | Yes (wash filters) | €150 – 200 |
| 4 | Indoor unit poorly fixed / not level | Leak on one side of the split only | Depends on install | €200 – 400 |
| 5 | Lift pump failed (wall or ducted) | Full tray, odd noise, safety cut-out | No (part to replace) | €350 – 700 |
| 6 | Refrigerant leak | Weak cooling, frost, oil trace, hissing | No (illegal without certification) | €400 – 1,200 (detection + repair + recharge) |
The first three causes cover the bulk of calls received by refrigeration technicians at the start of summer in Nice, when units restart after six months off and a biofilm plug has formed in the drain hose. According to installers on the French Riviera, this is the classic peak in May–June.
What can I fix myself?
First, switch the unit off and unplug it electrically (circuit breaker or plug). Then, in order:
- Clean the indoor unit air filters: open the front, remove the filters, wash in lukewarm soapy water, dry, refit. That single step handles a good share of leaks.
- Check the tilt of the indoor unit with a spirit level: it should tilt very slightly toward the drain outlet (right or left side depending on the model). A split installed dead level will never drain properly.
- Unclog the drain hose: at the far end (usually on the outside façade or in a sink), blow with a reversed vacuum cleaner or use a small flexible snake to dislodge the algae plug.
- Empty and clean the condensate tray: on a wall-mounted split, that means removing the front cover — often 2 screws + 2 clips. On a floor console, it is immediate.
If the unit is under warranty, do not dismantle anything yourself: opening the cover as a user can void some manufacturer warranties. On a ducted system or a ceiling-recessed cassette, do not try anything yourself: access to the lift pump calls for a professional.
When to call a refrigeration technician, and at what price in Nice?
Bring in a professional in these four cases:
- The leak persists after cleaning the filters, tray and hose.
- The unit is a ducted system, a cassette, or a recessed console (complex access).
- You suspect a refrigerant leak (oil traces, hissing, drop in cooling).
- The outdoor unit leaks (rare, but often linked to the refrigerant circuit).
In Nice and across the 06, the ranges observed early 2026 are:
| Intervention | Indicative price incl. VAT |
|---|---|
| Diagnosis + call-out (first hour) | €90 – 150 |
| Drain unclog + tray clean | €150 – 250 |
| Lift pump replacement | €350 – 700 (part included) |
| Refrigerant leak detection (nitrogen / UV dye) | €150 – 300 on top |
| Braze repair + R32 recharge | €300 – 700 on top |
Systematically check that the technician holds a refrigerant handling certificate (issued by an accredited body, mandatory for any intervention on the refrigerant circuit). It is that certificate that authorises them to open the circuit — not the mere status of tradesperson or plumber.
What does the law say if it is a refrigerant leak?
EU Regulation No 517/2014, known as “F-Gas”, tightly frames refrigerants. Its article 3(3) is explicit: operators of equipment on which a leak has been detected cannot recharge the equipment with fluorinated greenhouse gas until it has been repaired. Repair must happen “without undue delay” and a tightness check has to follow within one month.
In practice, a technician offering you a “simple recharge” without detection and repair of the leak is breaking the law — you are entitled to refuse. Every intervention on the circuit must be logged on an intervention record (article R543-82 of the French Environmental Code) stating quantities recovered and reintroduced, and jointly signed once the charge exceeds 3 kg. See also our dedicated guide on the price of a gas recharge in Nice.
FAQ — AC unit leaking water
Is it serious if my AC leaks water indoors?
No, not in the vast majority of cases. A clear, odourless water leak is condensate — the normal by-product of cooling air. The cause is a full tray, a blocked drain hose or a fouled filter, and it is usually solved in 20 minutes. It is very different from a refrigerant leak (oil, hissing, drop in cooling), which is rare but serious.
My AC drips, do I need to recharge the gas?
No. A water leak is never linked to the refrigerant. The gas circulates in a hermetic pressurised circuit: when it escapes, it goes into the air, not as water. If a professional offers a recharge without first checking the condensate circuit, get a second opinion — that is a red flag.
Can I keep using an AC unit that is leaking?
With a condensate leak, the unit still works but risks damaging your finishes (plaster, wood floors, furniture) and triggering the overflow safety, which cuts the AC. With a suspected refrigerant leak, stop immediately: carrying on lets more gas escape, worsens the fault, and puts you in breach of F-Gas if you recharge without repair.
How much does it cost to fix a leaking AC in Nice?
Expect €150 to €250 incl. VAT for a drain unclog and tray clean (the 3 most frequent causes), €350 to €700 for a lift pump replacement, and up to €1,200 if diagnosis reveals a refrigerant leak with braze repair and an R32 recharge. A clear quote must separate call-out, labour and parts.
Sources
- Regulation (EU) No 517/2014 on fluorinated greenhouse gases (F-Gas) — article 3(3) forbidding recharge before repair (EUR-Lex).
- French Environmental Code, section 6 “Refrigerants used in refrigeration and air-conditioning equipment” — articles R543-75 to R543-123 (Légifrance).
- Fluorinated refrigerants FAQ — French Ministry for Ecological Transition — duties of operators and equipment owners.
A leak to diagnose on the French Riviera?
Aircadia works in Nice, Cannes, Antibes and across the 06. Our technicians hold the French refrigerant handling certificate and always check the condensate circuit — the most frequent culprit — before suspecting a refrigerant leak. Clear, free quote within 48 h, plus a reminder of our useful guides: AC no longer cooling, price of a gas recharge and when to service your AC.