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996.1 Carrera 2 - Engine whine identified !?

iceboy

Well-known member
Joined
18 Apr 2013
Messages
387
Hi All,

After a lot of jiggery pokery.......I finally (as previously suggested) figured out the my Air Con is making the intermittent whining sound.

When the whining occurs, if I switch off the AC * on the dash, the whine stops immediately.

So the question is, what is making this noise, is it dangerous to the engine/car and what needs to be done??

Thanks in advance.
IceBoy
:?:
 
As you've said engine whine I presume you mean from the back end?

I think it's a low A/C gas level, probably due to a small leak in one of your condensers.

I hear exactly the same thing in my 996TT and whilst it still blows cold, when the car was in for a minor service the guy said there's a small leak in one of the condensers.
 
Agree with Gareth. My car (also 996.1 C2) was doing exactly the same thing. A/c would blow cold(ish) but the compressor sounded like it was labouring. Went and got the system tested and regassed, now works fine.

A/c systems do leak over time even when everything is fine. Mine passed all the pressure tests, just needed a gas topup. Approx cost of a test and regas should be about 50-60 pounds
 
Thanks guys!

The AC is nice and cold but I will get it re-gassed.

Am I right in thinking the re-gassing has some form or lubrication in it?

IceBoy
 
Yeah I think there's 2 parts to what goes into the system, the refrigerant itself and lubricating oil as well. I think that's correct?
 
About 25mls of lubricant.

A proper a/c service will take about an hour and involve removing all the a/c fluids, pressure testing, nitrogen flush and the separate replenishment of both the refrigerant and lubricant. Also a good technician will spend a fair bit of time with a UV torch looking for leak / spill evidence around condensers and filling points. A simple topup of refrigerant is not enough and could damage the system, because the refrigerant / lubricant mix needs to be correct. See if you can watch the procedure and ask questions, it's worth knowing about it.
 
Avon said:
About 25mls of lubricant.

A proper a/c service will take about an hour and involve removing all the a/c fluids, pressure testing, nitrogen flush and the separate replenishment of both the refrigerant and lubricant. Also a good technician will spend a fair bit of time with a UV torch looking for leak / spill evidence around condensers and filling points. A simple topup of refrigerant is not enough and could damage the system, because the refrigerant / lubricant mix needs to be correct. See if you can watch the procedure and ask questions, it's worth knowing about it.

Quick question .. how do you get the Pag oil out ?


Only asking as theres about 200ml in the system.

http://www.5150motorsport.com/porsche-a-c-refrigerant-capacity/
 
Demort said:
Quick question .. how do you get the Pag oil out ?

My understanding is that when the system looses gas and therefore has poor circulation by virtue of it having next to nothing to compress/boil the remnants of the oil settle out and usually show themselves with staining of the aircon rads?
 
Demort said:
I was interested to know how you get all the pag oil out with an A/C service thats all .. new one on me and always interested in tips ;)

Sorry mate - misread your earlier post.

If it's a straight regas then some of the oil is withdrawn with the refrigerant during the vacuum - it is important to measure what is extracted to ensure that it is not subsequently over oiled on regas.

Some numbers here:-

http://www.denso-am.eu/media/27145/denso-practical-tip-compressor-oil.pdf
 
Demort said:
I was interested to know how you get all the pag oil out with an A/C service thats all .. new one on me and always interested in tips ;)

My understanding is that if/when the system is vac'ed down to c. -1000mb, then fluids in the system (i.e. the gas and oil) will boil (at those low pressures) and be extracted by the vac pump.

It is commercial heat pumps in my equipment but I'm sure the same physics apply
We only use Nitrogen to leak test, removal of gas & lube is done by vac.

Changing to a different refrigerant in the same system is more complex as the lubricants can be incompatible.
 
I seem to have the same issue as the OP mentions and have come across this post through the search.

I plan to get the A/C system checked and regassed but wondered, can this be done anywhere (i.e an air-con specialist) or do you think the car should still go to a Porsche specialist?
 
I got a mobile air con specialist to do mine.

By all accounts the systems at Quik Fit are plug and play, likely the same unit a Porsche Indy would have anyway.
 
KwikFit will be fine for re-gassing, the question arises if there is an issue.

My car had a leak from a joint at the OSR, quite common as people jack them up carelessly under the pipe. 9E traced the problem and fixed it for me.

The other common areas for problems is the condensors, I changed mine, quite easy really but I wouldn't let Kwikfit near it.
 
Harvster said:
I seem to have the same issue as the OP mentions and have come across this post through the search.

I plan to get the A/C system checked and regassed but wondered, can this be done anywhere (i.e an air-con specialist) or do you think the car should still go to a Porsche specialist?

Kwikfit use an automatic Machine which pulls and tries to hold a vacuum to check for leaks, doesn't always catch small leaks But it's not bad. Depends where in Derbyshire you are, Loe bank motors in bury are worth the trip as the guy who runs it is also an air-con specialist as well as a Porsche specialist and no more than an average mobile a\c outfit
http://www.loebankmotors.co.uk/
 

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