Macbook Air Charging Problem

Your magsafe adapter plugs in to the magsafe board (I/O board).Could be that board, or the cable that connects that board to the logic board, or the logic board itself. My first guess will be the I/O board.
You have an almost-new system. Take it in for service, so you don't waste more time (and money) replacing wrong parts.
Accidental damage is not covered by the warranty, and the repair is not likely to be cheap.
Or, call AppleCare for some help. Even if you have taken your MBAir out of warranty, Apple should give you some idea about repair cost, or give you some options about getting it repaired. Then, it's your choice whether you want to pay to get it fixed.

tpmmg said:

But if i plug a 60W adapter, it maintain charging, it seems that the 45W does not have enough power to charge while running. Is there any component that prevents the passage of current.
Thanks

Click to expand...

Yes, of course!
1.The connectors. Check that the contacts on both the adapter, and the magsafe connector on your MBAir are both clean and undamaged.
The charging current has to go through that connection.
2. Next is the magsafe board (again, that's called an I/O board),
3. then the ribbon cable that connects the magsafe board to the logic board,
4. then (again) the logic board.
If everything else (as far as you know) is working OK, then using the idea that the liquid damage is the likely cause, then you want to check all the internal connections.
I haven't looked at any take-apart for the newest MBAir, but previous models have those connectors fairly easy to inspect just by removing the bottom cover on your MBAir. Did you already try that, just for your own information?