Hissing from air conditioning AC

Hi All,

I have a 02 plate Nissan micra SE. I brought this car about 6 months ago and never tested the air conditioning

Well now its hot I switched the AC on and the air was coming out normal (warm) and there was no noise from the engine bay.

I took the car to the mechanic who re-gassed the AC system and now when I turn on the AC there is a hissing noise from the engine bay just below the alternator.

The air in the car is colder but not great, I have switched the vents to fresh and recirculation and the noise is still there. And of cause when I switch the AC off the noise goes away.

I am not sure where to start; the guy in the garage suggested a possible block. There is a silver pipe that leaves the part that is hissing and enters the car (I guess this feeds the vents) and this pipe is cold.

Any suggestions help and advice would be much appreciated


Has gone over to the oily side...
Club Member
Sounds like a possible leak in the joint between the cold feed from the compressor into the cold matrix - if you lick your finger and move it around the hissing area, can you feel any leaking?


Site Supporter
May be worth posting in the K11 section (Y) , possible leak i reckon, you can get it leak tested.