Regarding a 96 Civic with LS swap. AC works fine however after it has been running for approximately 15 minutes (always the same amount of time) there is an unusual noise that comes from the AC related boxes behind the dash. It sounds sort of like air whooshing or a very very quiet air compressor building pressure. The AC continues to work fine as this happens. I've had dozens of Civic's and don't recall hearing this noise before. Could this be something to do with the evaporator?

 

You are hearing refrigerant spraying into the evaporator - not abnormal.

 

Would this noise be more pronounced if the freon is low? I have to check it later.

 

If your A/C works fine, I would do nothing.

 

thanks, i'll leave it be. the only reason i posted is because i hear this noticeable "injection" every 30 seconds or so only AFTER the AC runs for 15 minutes silently.

 

Post a video with sound or just sit back and enjoy a working A/C system.