No milk flow on a Delonghi Coffee Machine

It is very frustrating when your Delonghi coffee machine just will not suck milk and just spits instead of a steady flow. Small domestic coffee machines use the Venturi Effect to suck milk and mix it with air to create froth. This requires a good steady flow of steam.
So your first action is to ensure you have adequate steam volume. If you do then you can look at the coupling device or milk jug as being the problem.
But here we are concerned with poor milk flow caused by a lack of steam. There are various methods to assess the steam volume. I usually decouple the steam line and make a milk beverage. You probably know the usual steam output from you machine, so it will be obvious if there is not the usual steam output.
In the Delonghi Authentia, the steam is produced in the horse shoe shaped flash boiler. The first thing you should do is ensure this is hot and heating. It will be or there will be no steam at all. It could be that the NTC temp sensor is faulty and the boiler is not hot enough. But this is not a usual fault.

The most likely issue will be scale build up on the outlet of the flash boiler. Zoom in on the photo below showing scale almost completely blocking the outlet side of a Delonghi flash boiler. This machine had very little steam output.

deLonghi coffee machine flash boiler scale blockage

This thermoblock had to be replaced and it resolved the issue. If the steam thermoblock is ok then I would suspect the electrovalve on the steam output. This may be blocked or not opening. The inlet electrovalve that lets water into the flash boiler may also be blocked and not functioning. Occasionally I have found steam tubes blocked with scale as well.

If you require your Delonghi Coffee Machine Serviced. Please call us at Outwest Coffee and we can repair it for you. We are in North Lakes, north of Brisbane and are open Saturdays.