Hi, I took my 2017 Fiesta in for a major service earlier this year and immediately after the aircon started making a hissing sound, and after 2 weeks of light use, would only produce hot air. I took it back to the garage who insisted they hadn't touched the aircon in the service, so I booked it in for a diagnostic where they tested for any leaks etc in the aircon. I had been assured there were no leaks after the tests and paid to have it re-gassed - But the problem still persists! The noise is pretty constant when the aircon is on, apart from when my accelerator is fully down. It is loud enough that I can hear it very clearly over the radio etc. The noise seems to be originating from behind the dashboard. I know that the gas will run out soon again, so any thoughts on this issue would be greatly appreciated!

Has anyone else had this issue, or have any solutions please?!

I had pretty much the same issue on a 2011 Fez, I could hear the same sound you’re talking about, coming from the passenger side footwell (EU version, so it should correspond to the drivers side for the UK version) and in the end I had a very very tiny leak in one of the AC pipes, so I ended up replacing the 2 pipes. I had a garage do the work and it cost around €300