The problem: a laptop that would not power on — and a wet desk
Short answer: Air conditioning units produce condensation — water extracted from humid air as part of the cooling process. This water is supposed to drain through a pipe to the outside. When the drain pipe is blocked or the unit is slightly misaligned, this water drips from the front face or the pipe fitting, directly downward. A laptop left on a desk under such a unit receives a slow, continuous drip for the entire duration the AC runs. By morning, the keyboard tray has pooled with water that has been absorbing into the board through the keyboard gaps for 6 to 8 hours.
Three bench cases from overnight AC drips
Case 1: The MacBook Air that would not wake up
A professional left their MacBook Air M2 on their home office desk overnight with the AC running. The AC unit above the desk had a partially blocked drain — a slow but steady drip. They woke up to find a small puddle on the desk and their MacBook unresponsive. The condensation water had dripped precisely onto the keyboard, entered through the gap between the keys, and pooled around the audio controller IC and USB-C charging ports on the logic board. Condensation water is slightly acidic compared to clean tap water because it picks up traces of aluminium oxide and mould spores from inside the AC unit, making it marginally more corrosive. The board required ultrasonic cleaning and one USB-C controller IC replacement: ₹7,200. The machine was recovered fully.
Case 2: The office Lenovo with corroded keyboard matrix
In a shared Hyderabad office, a Lenovo ThinkPad E14 was left on a workstation desk under a wall-mounted AC unit that had been dripping onto a potted plant for weeks — the plant was just catching most of it. Over a holiday weekend, the plant was moved and the AC dripped directly onto the keyboard for three days. When the employee returned, the keyboard was completely non-functional and the desk surface had a dried mineral deposit ring showing exactly where the drip had landed. The keyboard matrix (the electrical grid under the keys) had fully corroded. Keyboard replacement plus board clean: ₹3,800. The board itself was undamaged — the keyboard had acted as a sacrificial layer, which is unusual and fortunate.
Case 3: The laptop at a coastal office — corrosion accelerated by salt air
A Visakhapatnam-based customer brought us a Dell Latitude that had been placed below a dripping AC unit in an office building near the beach. Coastal air contains dissolved salt — common table salt (sodium chloride) — which enters AC units, concentrates in the condensation water, and deposits as a highly conductive residue on electronics. The drip had lasted only one night but in salt-air conditions the corrosion was more severe than we typically see from pure condensation. Multiple resistors and a capacitor on the charging circuit had shorted through salt-bridge corrosion — where the conductive salt deposit creates an unintended electrical path between adjacent components. Chip-level repair plus ultrasonic clean: ₹5,400.
Prevention and the India context
This damage pattern spikes in India during the April–September high-AC-use season. Most AC units in Indian homes and offices are serviced once a year if at all — clogged drain pipes are extremely common. The fix costs under ₹500 at an AC service call. The resulting laptop damage costs many times that. If your AC unit has ever left a wet patch on the wall or floor below it, get the drain pipe cleared before the next monsoon season starts, and move your electronics away from the area below the unit. See our broader notes on AC condenser water damage bench cases for the full seasonal pattern.
The response protocol after discovering an overnight drip is the same as any spill: power off, disconnect charger, and bring to a repair service within 24 hours. The extended contact time means corrosion may already have started, so speed still matters. A liquid damage repair assessment starts with a doorstep visit.
When to call a repair service and what it costs
When to act
Bring the laptop in if: the keyboard keys feel sticky or produce incorrect characters after an AC-near placement, the laptop does not respond to the power button the morning after running AC overnight, or you find any moisture on or around the machine and the AC unit above it shows signs of dripping.
Typical repair costs in India
Ultrasonic board cleaning plus corrosion removal: ₹1,500–₹3,500. Keyboard replacement: ₹1,500–₹4,500. Chip-level repair for corroded ICs: ₹2,000–₹6,000. Full assessment doorstep visit: ₹149.
A note from the LRW Engineer Team
Of all the preventable damage patterns we see, AC condensation is the one that frustrates us most — because the prevention is so simple. Never place a laptop on a surface below an AC unit. This is true for offices, bedrooms, and home studios. The risk is not theoretical: we see two to four of these cases every month across India, year-round, with a summer peak. Move the laptop or fix the AC drain. The two cannot coexist on the same desk indefinitely.