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Air Conditioning efficiency

Old 01-10-2019, 05:25 AM
  #16  
mike cap
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Originally Posted by chartwell View Post
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.
Good news. Get one of those cheapo dial probe thermometers and slide it into the center vent and watch the temps for a while. Hard to judge by feel. Previous was a chart of ambient versus vent temp. But watch for 7 to 12 C depending on ambient. Assumes good rpm, operating for a bit and MAX settings. Make sure you get good condensate water (drip) from under the car.
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Old 01-10-2019, 11:15 AM
  #17  
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"He found hardly any dye in the system" The system does not come with dye. Dye is added to the system when it suspected to have leaks. Unfortunately "dye" is only visible where you can see it, and there are many places you cannot see. So, rather than use dye what it s better to use an electronic leak detector; but you also need to know where to 'sniff', where all the connection points are and which are the most common leak areas (evaporator, TEV - expansion valve, condenser).

"so re-gassed the system " If he added refrigerant then you know you have a leak ....which he did not find. If he pulled a vacuum and recharged and now everything is okay, then chances are you still have a leak and its just a matter of time before you start observing cooling issues again.

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Old 01-11-2019, 11:48 AM
  #18  
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since griffiths jumped into this conversation, and are the a/c experts, i'll ask them.

would you guys expect a properly functioning 993 a/c system to be able to cool a black car with a black interior that has sat in the Arizona sun and reached probably 140+ F degrees or more in the interior?

(my experience in that condition is the vents blow cold but just cant overcome the residual heat of everything in the cabin and by the time i get home after a 10 mile drive through the city i am uncomfortably hot. my assumption was that this system just wasn't designed with the southwest desert in mind but Meenrod's account seems to suggest it's actually possible to be comfortable.)
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Old 01-11-2019, 12:30 PM
  #19  
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Fortunately here in NJ we don't see many days like the south. Highest we have tested systems was 103F to 105F (this would be on blacktop) with the earlier 911 generation.
And, I recall my black top (red body,tan interior) 87 911 cab's interior reaches 130F easily on a clear 85-90F day. So, I would imagine if you have black on black in TX on clear 100F day
those cabin temps might be higher than 140F. Answer, I have not confirmed if the 993 can handle it. But, I'd suggest using a good digital thermometer, something like a Traceable Products
model 4339 or 4039 which has a 10 foot cord from the head to the probe ; quite versatile for many things, and verify the outside ambient walking around the car and the interior.

If your outside ambient is, for example, 100F, and the cockpit is 140F, its quicker to let mother nature cool off that first 40F by simply driving with windows down for the first 5 minutes
until the evaporator core is chilled (no sense putting the load on the system). And, when a car is parked with windows up, best to leave them a crack open (unless you concerned about
crawling critters getting inside).

It would be interesting to hear if anyone has tried one of these gadgets:






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Old 01-12-2019, 11:43 AM
  #20  
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thanks for the response. using sun shades plus airing the cabin out do help. i've never tried the solar ventilators. luckily we've got 5 months before we have to start worrying about it again.
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Old 01-12-2019, 11:48 AM
  #21  
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Looks like you have a nice 991 to drive on the hot days and keep the 993 for real driving days!

fwiw I'm in Texas and my experience on super hot days the 993 when functioning correctly will not cool like a modern car. Especially if sunbaked. If your ride home is short you are going to be hot all the way.
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Old 01-12-2019, 07:40 PM
  #22  
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i do joke that the reason i bought the 991 is for the A/C.
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Old 01-14-2019, 06:27 PM
  #23  
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Originally Posted by JB 911 View Post
Looks like you have a nice 991 to drive on the hot days and keep the 993 for real driving days!

fwiw I'm in Texas and my experience on super hot days the 993 when functioning correctly will not cool like a modern car. Especially if sunbaked. If your ride home is short you are going to be hot all the way.
JB is 100% correct.
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Old 01-14-2019, 06:53 PM
  #24  
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On my car, I notice when the blower is set to high the temperature at the vent rises a little suggesting the capacity of the system is being reached.
A while back I used a wand style bug sprayer to clean the accumulated dust and mold on the evaporator coil in my car. I accessed it through the vent in the firewall behind the climate control unit. Others have done the same accessing it via the driver's side blower housing by removing the cabin filter.
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