Hi, i have a 2002 S80 NA noticed a hissing in my car 2 months agoand later my braking became harder. So i first asked here and found out it could be a brake booster so iwent to a local garage that specializes in saabs and volvos and their diagnostics showed it was a broken booster so i ogt that replaced and my braking improved tremendously! but when i have my AC on and stop the car at a red light between 2 aqnd 3 thousand rpms while accelerating i here a hissing. when i got the car 2.5 months ago i replaced the cabin air filter. could an error in my installation be causing that hissing ill probably take it ot the shoip but ijust wanna get some expert non biased opinion from the nice people on this site

 

I have 2001 s80 2.9 non turbo Mine has the same hiss. I have found out if you turn the air off it will not do it. An ac man told me he thought it was a bad stem in the ac line. would require draining the feron replace stem and pump down and replace feron. Has offered to do this for 75.00 will let you know when I get it done

 

Could be just refrigerant noise from A/C also recommend to see if there is a leak in A/C system.

 

how much did the booster replacement cost, i am going to have to do that for my t6

 

I had mine replaced by Richards Import Store in Gainesville Fl for 450.00 they work on nothing but Volvos

 

you could have a bad vacuum line in the a/c system as well..

 

To my knowledge I don't think there are vacuum lines for S80 for the A/C system. Air flow is control by damper motors... 700 and 900 series back then have vacuum valves and lines... (pain to fix and find leak) since volvo released front wheel drive vehicle there at no vacuum lines to control air flow.