machine turns on but no water comes out of either spout, just a clicking sound

Diagnosis

The clicking sound you hear is the internal vibration pump attempting to engage, but it is encountering a "vapor lock" or a physical blockage. When the pump clicks but no water flows, it means the pump is unable to create the necessary vacuum to pull water from the reservoir into the heating thermoblock. This is most commonly caused by air bubbles trapped in the internal plumbing (airlock) or a severe accumulation of calcium carbonate (limescale) that has physically bridged the narrow aperture of the heating element. Another frequent culprit is a blockage at the piercing needle or the exit nozzle. If coffee oils and fine grounds have solidified over time, they create a waterproof plug. You can confirm this by checking if the pump sound changes from a sharp "click-click" to a muffled hum; a muffled hum usually indicates the pump is working but the water is blocked by a clog, whereas a rapid clicking often points to an airlock in the pump head.

How to Fix It

To resolve this, you must first clear the physical pathways and then force the pump to prime. Follow these steps exactly:

1. Clear the Capsule Path: Open the machine head and remove the capsule. Use a straightened paperclip or the cleaning pin to gently poke into the piercing needle (the sharp point that punctures the capsule) and the exit nozzle where the coffee drips out. Ensure there is no compacted coffee "puck" blocking the hole.
2. Deep Clean the Seals: Remove the drip tray and the used capsule container. Use a damp, lint-free cloth to wipe the rubber O-ring seal around the capsule holder. If the seal is dirty, it can cause a pressure leak that prevents the pump from priming.
3. The Forced Prime Method: Fill the water tank to the maximum line and ensure it is seated firmly. Place a large container under the spouts. While the machine is on, press the "Hot Water" or "Milk" button repeatedly in quick succession. This rapid cycling can sometimes "jolt" the air bubble out of the pump.
4. The Water Tank Trick: Lift the water tank slightly while the pump is clicking, then drop it firmly back into place. This sudden change in pressure can break the surface tension of an airlock and allow water to enter the pump head.
5. Manual Air Purge: If you have a handheld bulb syringe (like those used for infants), fill it with warm water and gently press it against the water intake valve at the bottom of the machine (where the tank connects) to force water manually into the internal lines.

If That Didn't Work

• Chemical Descaling: If the pump eventually starts but the flow is a trickle, the machine is scaled up. Use a citric-acid-based descaling solution. Fill the tank with the solution, run a full cycle, and let the machine sit for 30 minutes with the solution inside the thermoblock to dissolve the calcium bridges before rinsing with three full tanks of fresh water.
• Check the Water Tank Valve: Inspect the small rubber gasket at the bottom of the water tank. If this gasket is pinched or cracked, the pump will suck in air instead of water, causing the clicking sound. Replace the gasket or ensure it is seated perfectly flush.
• External Pressure Method: Some users find success by using a clean turkey baster to force water directly into the machine's intake valve while the pump is running. This overcomes the airlock by providing the initial "push" the pump needs to grab the water stream.
• Hard Reset: Unplug the machine from the wall for at least 60 seconds. While unplugged, hold the power button for 10 seconds to discharge any remaining electricity in the capacitors. Plug it back in and attempt the "Hot Water" cycle immediately.

Heads Up

• Avoid Distilled Water: Never use 100% distilled water. The Lattissima One's pump requires the mineral content of water to maintain proper pressure; distilled water can actually lead to more frequent airlocks.
• Weekly Rinse: Run a "water-only" cycle (without a capsule) once a week to flush out residual coffee oils that cause the exit nozzles to clog.
• Scale Warning: If you live in a hard-water area, descale every 300 capsules. Ignoring the descaling alert is the primary cause of pump failure and the "clicking" symptom.
• Tank Seating: Always ensure the water tank is pushed down completely. Even a 2mm gap can allow air to enter the system, killing the pump's prime.