blkvet6

When my C6 (with auto climate control) was new, I would hear A/C "hissing" type noise after shutting off the vehicle. Dealer replaced the A/C compressor (under warranty) - but now no "hissing" sound. The A/C is perfectly quiet after shutting off the engine. Is that correct? Does your A/C make noise after vehicle shut-off? Or is your A/C quiet after shut-off? (A/C seems to be working / cooling OK, it's just no longer making the hissing noise. = Is that correct operation?)

glenB

They do that, should they ? the general answer is no, but they do.

The 'hissing' is the system equalizing. AC has a high/low operating pressure system.

Could you build a case the the sytem is restricted? You could, most common is the Oriface Tube, it will catch 90% of what's floating it the system if something internal is coming apart.

But I have heard systems making the noise on perfectly fine AC.

danl72

No it should not do that.

Joe Lynch

Mine hisses but it my case it is normal because the condenser drain drips on the headers.

Pylons

Mine does that too, as did a car I test drove.

*FAÇADE*

JoesC5

yes, if the neighbor's cat is trapped under the hood.

'VETTE PHASE

It must be nice to still be running the A/C.

Hockeybumjack

I just replaced the compressor, condenser, dryer and orifice tube. I flushed out the evaporator and other tubes. I replaced all O-rings. There are no leaks. The high/low numbers are very good with respect to ambient temperature. It cools really well. There is a hiss when I shut it off, for about 5 minutes, (I haven't actually timed it). I have no concerns about the hissing noise.

Crow Hunter

When the AC condensate drips on hot exhaust parts there is often a hissing sound.