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Air Conditioning efficiency

Old 12-30-2018, 05:17 AM
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chartwell
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Default Air Conditioning efficiency

Hi,
My name is Chris from Sydney Australia and a new owner , five months ago, to the 993 Porsche circle. Today my wife and I went for a drive for 150 kms but it was not a happy experience for her as the A/C didn't produce cold air. Is the A/C in the 993 comparable to other contemporary vehicles, or should I have the system checked out? Bearing in mind that it was 36 degrees celcius , but the system was serviced with a re-oil and re-gas just 12 months ago. My car is a standard 993 C2 Tiptronic, Aventurine, 17" Cup alloys, and full Caramel leather trim. Thanks for any thoughts.
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Old 12-30-2018, 06:36 AM
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ToreB
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Chris, welcome to Rennlist!
It should be no problems to use your car in such conditions, with normal cabin temperatures.
There are many things that can fail in the 993 HVAC system. Most, if not all of the culprits are known and well documented.
Have a look here for details and a DIY test procedure.

Cheers,
Tore
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Old 12-30-2018, 12:34 PM
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jfischet
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Hi Chris. Welcome.

I have a 993 in Arizona and the temps get as high as 120F (48C) in the summer. When I first bought it, the A/C did not work well at all. It took a lot of labor to get at the root of the issue with the expansion valve, which can only be accessed by removing the fuel tank and working back towards the dash. It cost about $3k, mostly labor.

The A/C now works quite well in the 90s to low 100s and tolerable above that, provided the car is parked in the shade and is moving at 45mph or above. It's still no fun at all if sat in the sun for a few hours and then driven in stop and go traffic.
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Old 12-30-2018, 12:39 PM
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Mine works amazing. Would actually say too cold sometimes. 96 turbo
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Old 12-30-2018, 01:28 PM
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Meenrod
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I live in South Texas and we regularly see 40c in Summer. My AC keeps the interior cool regardless of speed, shade, direct sun etc. And it's a black car with black interior. And a daily driver.
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Old 12-30-2018, 09:43 PM
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chartwell
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Default Air Conditioning Efficiency

Thank you for all of the prompt replies, this forum is great! It appears as though I'd best have an Air Con service centre check the car out, however it's difficult to be confident that any particular place has experience with Porsche. Thanks again, I'll ask around ,and report back.
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Old 12-30-2018, 11:31 PM
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mike cap
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Best to find an air cooled P shop and not an AC specially shop. You’re more likely to have good luck with someone that knows the screwy 993 systems.

The AC is robust enough in hot humid weather to cool the cabin. It can be noisy running the fans on high to cool though since the system is not exactly overkill.

As a point of reference you can measure the center vent temp and look for 48 to 50 F ’ish at decent engine rpm and with system set at MAX. Your local Home Depot type store in the HVAC dept sells a cheap probe style thermometer that the HVAC service guys slip into vents to measure temps. One of these will fit nicely in the center vent and it’s a good judge of system health.

When parking I use a sunshade to try and keep the cabin from heat soaking. With the big windscreen it helps a lot.
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Old 12-30-2018, 11:39 PM
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Meenrod
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Originally Posted by mike cap View Post
Best to find an air cooled P shop and not an AC specially shop. You’re more likely to have good luck with someone that knows the screwy 993 systems.

The AC is robust enough in hot humid weather to cool the cabin. It can be noisy running the fans on high to cool though since the system is not exactly overkill.

As a point of reference you can measure the center vent temp and look for 48 to 50 F ’ish at decent engine rpm and with system set at MAX.

When parking I use a sunshade to try and keep the cabin from heat soaking. With the big windscreen it helps a lot.
Good point Re sunshade. I forgot to mention I use one too on really hot days.

​​​​​But when is the US gonna get with the rest of the world and move to the metric system?!
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Old 12-30-2018, 11:48 PM
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mike cap
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Ha, yeah I’m metric on my bikes and the 993 but revert at times. I just knew that 48 to 50 F figure from memory and the P service bulletins as a close to nirvana temp at 80 F + ambients.
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Old 12-30-2018, 11:53 PM
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No sweat just pulling yer leg!
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Old 12-31-2018, 12:54 AM
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I would first check the obd codes for the hvac system to verify the heating and fresh air servos are working so hot air is not being introduced into the cabin diluting the effectiveness of the AC
​​​​​​. The codes can be read with Durametric software &cable. Then check the system by measuring cabin vent temperatures with a thermometer so one knows if the issue is warm vents or simply a heat soaked car body.
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Old 12-31-2018, 10:58 AM
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There are a few Porsche repair shops around Sydney that should be able to quickly diagnose if there is an issue and what the likely causes are.

Just call them up and ask if they do their AC work on site or do they job it out.

If they do it on site they should have an evacuation and charging machine or equipment, electronic leak detectors, and so forth.
Typically they will determine if the compressor clutch is engaging, if so what are the pressures, verify hvac codes using software and lap top or the Porsche hammer,
sniff for leaks, check vent temps and other performance observations.

here are a few shops you can call.

http://www.prtechnology.com.au/

http://www.buchananautomotive.com.au/

https://bwaauto.com.au/

Last edited by griffiths; 12-31-2018 at 06:46 PM.
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Old 12-31-2018, 05:50 PM
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Originally Posted by Meenrod View Post
No sweat just pulling yer leg!
I know no worries. Metric is so much easier. Besides biking overseas 50 km sounds like so much further than 30 miles.
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Old 12-31-2018, 08:22 PM
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OP, there's a factory spec for vent temps at a given ambient air temp. The post below has the relevant graphs. In my experience 993 AC is mediocre and if you're cruising around in hot, very sunny conditions, it struggles to keep up. It also doesn't work very well at idle, because the compressor isn't being spun fast enough.

https://rennlist.com/forums/964-foru...tml#post723852
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Old 01-10-2019, 05:12 AM
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chartwell
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Originally Posted by chartwell View Post
Hi,
My name is Chris from Sydney Australia and a new owner , five months ago, to the 993 Porsche circle. Today my wife and I went for a drive for 150 kms but it was not a happy experience for her as the A/C didn't produce cold air. Is the A/C in the 993 comparable to other contemporary vehicles, or should I have the system checked out? Bearing in mind that it was 36 degrees celcius , but the system was serviced with a re-oil and re-gas just 12 months ago. My car is a standard 993 C2 Tiptronic, Aventurine, 17" Cup alloys, and full Caramel leather trim. Thanks for any thoughts.
Just a quick update. I had a Porsche mechanic , who now operates his own mobile service , come and check the air -conditioning. He found hardly any dye in the system, so re-gassed the system adding a dye. He then ran the air for 30 mins with no leakage on the high pressure side, the tested for vacuum, where it held pressure , also with no loss. So his conclusion is to use as per normal, monitor the temp output, and if it drops off he can then check with his U/V light for any signs of leakage. In the meantime it's pumping cold air. Thanks for all the helpful replies.
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