If your car is making a whining noise .. a rumble .. a noise like a worn bearing then try switching off the a/c .
If the noise goes then the fault is probably low a/c gass .
To test your car i find a temp of 19.5 with a fan speed of 3 .. give it a few mins on idle .. if you then hear a noise that stops when you switch off the a/c then its low gass .
A/c gass .. which on these cars is R134a will have an annual loss of 10% per year .. you don't have a leak as such but its the normal escape of gas from the system.
If your car hasn't been regassed in several years then you can see it is already low and you have probably gotten used to any noises .
Leak areas .. obviously it can leak from any part of the system but the main 2 places are the front condensers and the o/s/r pipe connections .. just in front of the o/s/r wheel and under the panel .
Condensers and you have to replace them .. see the image below for " damp spots " these are small leaks and will have an oily / dirty look to them .. if you are lucky you will see sighs of green .. that's the dye used to show leaks .
Rear pipes and its corrosion thats causes leaks .. if you are lucky and can get the bolts out then clean the surfaces .. scotch brite , new seals and refit .
Its not uncommon for these pipes to have pin hole corrosion at this joint though .. new seals wont help there .. your looking for a black spot on the pipe .. the more you dig at it the more white powder will come out .. that's ally corrosion .
You also use this test on any a/c pipe in a bracket .
The system holds 900 grams of R134a and 195 cm3 of oil .. ml .
The oil coats the inside of all the components .. its like a mist and is used to lubricate the compressor .
When degassing a system you will get some out but you will never get it all out hence we add oil as per the chart when items have been replaced .
A vacuum to the system will make moisture boil .. this can then be sucked out .. oil doesn't boil in a vacuum .
Fans will run at low speed when the a/c is turned on regardless of whether the system is working or not .
Fan info can be found here ..
http://911uk.com/viewtopic.php?t=127681&highlight=
If the car has been left open to atmosphere or has been empty for a while then its wise to replace the dryer along with what ever work you are doing .
A/C rubber seals on the pipes .. these are designed to swell on contact with Pag oil .. always replace them when undertaking any work .
oil used is pag oil 46 .
When replacing a compressor .. the new one will come pre filled with the entire amount of oil for the system .
You drain this out of the new compressor , you drain out the oil from the old compressor and measure it .. you then refill that amount of oil into the new compressor and fit it.
Never .. ever just fit a new compressor out of the box .. it will hydro lock it and destroy it ... this is for every car .. not just Porsche .
Images below show the system , the amount of oil per component that needs adding as a percentage of 195 cm3 , condenser leak and a few that i feel might be useful .
Image from Pelican and the black / red arrow shows the rear pipe connection although LHD .
Gratitude to Pelican for their image and a well respected site that i think we all refer to .
I did say i would do a write up on a/c in the past .. sorry it took me a year .. i have a back log of things to do
If the noise goes then the fault is probably low a/c gass .
To test your car i find a temp of 19.5 with a fan speed of 3 .. give it a few mins on idle .. if you then hear a noise that stops when you switch off the a/c then its low gass .
A/c gass .. which on these cars is R134a will have an annual loss of 10% per year .. you don't have a leak as such but its the normal escape of gas from the system.
If your car hasn't been regassed in several years then you can see it is already low and you have probably gotten used to any noises .
Leak areas .. obviously it can leak from any part of the system but the main 2 places are the front condensers and the o/s/r pipe connections .. just in front of the o/s/r wheel and under the panel .
Condensers and you have to replace them .. see the image below for " damp spots " these are small leaks and will have an oily / dirty look to them .. if you are lucky you will see sighs of green .. that's the dye used to show leaks .
Rear pipes and its corrosion thats causes leaks .. if you are lucky and can get the bolts out then clean the surfaces .. scotch brite , new seals and refit .
Its not uncommon for these pipes to have pin hole corrosion at this joint though .. new seals wont help there .. your looking for a black spot on the pipe .. the more you dig at it the more white powder will come out .. that's ally corrosion .
You also use this test on any a/c pipe in a bracket .
The system holds 900 grams of R134a and 195 cm3 of oil .. ml .
The oil coats the inside of all the components .. its like a mist and is used to lubricate the compressor .
When degassing a system you will get some out but you will never get it all out hence we add oil as per the chart when items have been replaced .
A vacuum to the system will make moisture boil .. this can then be sucked out .. oil doesn't boil in a vacuum .
Fans will run at low speed when the a/c is turned on regardless of whether the system is working or not .
Fan info can be found here ..
http://911uk.com/viewtopic.php?t=127681&highlight=
If the car has been left open to atmosphere or has been empty for a while then its wise to replace the dryer along with what ever work you are doing .
A/C rubber seals on the pipes .. these are designed to swell on contact with Pag oil .. always replace them when undertaking any work .
oil used is pag oil 46 .
When replacing a compressor .. the new one will come pre filled with the entire amount of oil for the system .
You drain this out of the new compressor , you drain out the oil from the old compressor and measure it .. you then refill that amount of oil into the new compressor and fit it.
Never .. ever just fit a new compressor out of the box .. it will hydro lock it and destroy it ... this is for every car .. not just Porsche .
Images below show the system , the amount of oil per component that needs adding as a percentage of 195 cm3 , condenser leak and a few that i feel might be useful .
Image from Pelican and the black / red arrow shows the rear pipe connection although LHD .
Gratitude to Pelican for their image and a well respected site that i think we all refer to .
I did say i would do a write up on a/c in the past .. sorry it took me a year .. i have a back log of things to do