Honda Accord losing coolant if aircon is turned on

I have a 2007 Honda Accord Euro all of a sudden now loses coolant whenever I use the aircon. When I drive with the aircon off, the level remains fixed but soon as I drive 20min with ac I realise the overflow reservoir is way below minimum. I can smell coolant when I open the bonnet but I cant see where it could be leaking.

I asked one mechanic and he said there is no relation between losing coolant and running ac. Any ideas what the issue could be?