Whining Air Con

[river_rat]

996 C4S bought with air con not working.

Was intending to leave it until March/April but misting up without so took it to local garage who vacuum tested system with no evidence of leaks and re-gassed it, although did mention the vacuum test can temporarily seal a leak which will open up when the system is operating.

All seems to be working OK but makes a noticeable whining sound which gets worse at 2k revs, then seems to drop away (or get drowned out by sports exhaust). If I turn air con off but leave fan on the noise immediately stops, then starts as soon as air con switched on again.

I've seen various internet solutions ranging from compressor, pulleys to leaking condensor(s) - I'm veering towards condensors bearing in mind system was completely out of gas when tested.

Anyone else had this? I'm assuming a proper leak test to identify leak(s) is only realy solution?

[davek_964]

I had the same thing, and I assumed it was my compressor whining. However, I discovered I had a leaking condensor - had that replaced, system recharged and the a/c was silent again.

[anonymous-user]

My 996C2 had an aircon pipe replaced and for a few drives afterwards I did get a whine from the compressor, however that has gone away and I was informed that it is quite normal for the compressor to make some noise. My AC had been broken for a while so I wondered if it was just noisy whilst the charge of oil circulated around the system and got to all the right bits.

[Lgeni1664]

Well, I was told that the whine can be due to the gas being low.

Had it tested, no leaks, but only 200 gms of gas.

Now full, the whine has gone.

[porkyspecialist]

Lgeni1664 said:

Well, I was told that the whine can be due to the gas being low.

Had it tested, no leaks, but only 200 gms of gas.

Now full, the whine has gone.

If there were no leaks then where did the missing 750g of gas go?

To the OP, get some dye in there & make sure the proper amount of gas was put in on the regas, porsches take more than most others so if you went to a generic garage they may of guessed the amount.

[Lgeni1664]

porkyspecialist said:

If there were no leaks then where did the missing 750g of gas go?

To the OP, get some dye in there & make sure the proper amount of gas was put in on the regas, porsches take more than most others so if you went to a generic garage they may of guessed the amount.

I thought that too. However, it has had new rads etc, so might have leaked then. And the last time it had it Ac done before me was 5 years ago, which is quite a while.

But of course, it may well have a leak-we will see.

[F3RNANDO]

Sounds like a slow aircon leak.
Probably from condensors or around joins in the fore/aft pipe work which you can see running the length of the car under the driver side just in board of the jacking points.
High street aircon guys with a plug in machine don't get a high enough pressure to locate a tiny leak, you need a specialist to drain the gas and pressure test and then fix the leak site.

Or you can continue to have the system topped up and let it slowly leak.
The compressor will whine as it has to work harder as the gas level drops until it reaches the low level when the compressor will no longer kick in and silence will return but the aircon will not cool.

I'd have to say the aircon design on these cars is very poor.

[Rockster]

river_rat said:

996 C4S bought with air con not working.

Was intending to leave it until March/April but misting up without so took it to local garage who vacuum tested system with no evidence of leaks and re-gassed it, although did mention the vacuum test can temporarily seal a leak which will open up when the system is operating.

All seems to be working OK but makes a noticeable whining sound which gets worse at 2k revs, then seems to drop away (or get drowned out by sports exhaust). If I turn air con off but leave fan on the noise immediately stops, then starts as soon as air con switched on again.

I've seen various internet solutions ranging from compressor, pulleys to leaking condensor(s) - I'm veering towards condensors bearing in mind system was completely out of gas when tested.

Anyone else had this? I'm assuming a proper leak test to identify leak(s) is only realy solution?

The system must be placed under a vacuum for 30 minutes and then if no leaks found refilled with the proper amount of refrigerant and compressor oil then pressure tested.

If just refrigerant replaced the compressor could be low on oil and this will damage the compressor.

Sincerely,

Rockster.

[bullettneil]

my c4s has a small leak according to the opc and when the system is on it has a whine that rises in noise when i deaccelerate at junctions. am i to assume that this is cause dby the leak then?