Hissing sound from the vents and weak A/C

[IdiotSavant]

Hello again

 

For quite a while now, with my 99 Legacy GT, I've been tolerating a hissing sound coming from the vents in the cabin. Even after the engine is shut off, the sound sometimes lingers for a few seconds.

 

Also, last summer I noticed my A/C is practically non-existent. Not sure if this is somehow related to the hissing. Maybe a leak somewhere that is preventing the conditioned air from reaching the cabin as well as the hissing sound?

 

For the A/C can it be as simple as replacing/filling the refrigerant or is it possible I'm looking at a more serious problem (i.e. compressor, etc)?

 

I have an appointment at Subaru tomorrow so I will definitely get this all checked out, but I like being somewhat informed before talking to the service advisor.

 

Again, I really appreciate all your help.

[ericem]

I know with my dads 04 nissan titan the A/C likes to hiss. With my 93 and 94 legacy they do not hiss at all though! I doubt it would be related to a leak though. You can recharge it using bottles on shelf.

[nipper]

You have a refrigerant leak under the dash.

 

 

nipper

[Legacy777]

More than likely what you are hearing is the flashing of the liquid refrigerent to a gas across the expansion valve. Normally you don't hear this because the regular amount of refrigerent needed to provide adequate cooling is designed not to create excess noise across the expansion valve. However if you're low on refrigerent the expansion valve will have to flow more refrig. through it to provide similar cooling capacity.

 

I'd suggest checking the pressures on the system, and probably having some refrigerent added.