A/C Pressures and amounts 4 930's

[Benny771]

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HI:
Anyone know the pressures and amounts of freon....
I have looked in a Bentley book i have for a 911 (not a 930) It states.
47oz of R12
Low side 12-30 psi
High side 115-205 psi Both at 25 degrees.
Freon amounts were not listed in my "free down-loadable" 930 shop manual.

Just wondering if this is the same for a 930, 1989.

What "vent" temp should i be getting if all is well? Apparently the P-cars don't cool as well as others. So I would like to know what is good for this car.

On my Vette 42 was pretty good

[scottb]

I got these numbers from Jim Sims, if I recall correctly. These numbers, I believe, are for a 911 (and I don't know if there's a difference). Also, of course, they're in Fahrenheit. Does the 930 use the same compressor as the 911?

Do a search on Jim Sims' name here on the board. Also MThomas58. They're a couple of REALLY sharp a/c guys, but I don't know if they have info on a 930. Also, Charlie Griffiths at www. griffiths.com is a great source of components and information. He posts on the board under the name Kuehl.

Also, does your car have barrier a/c hoses? If not, the factory hoses were permeable and pumping in expensive (and environmentally-unfriendly) R12 won't do you much good over the long run, as the R12 will slowly leak out.

Your comment about Pcars not cooling as well as other cars may be the understatement of the year. Our cars have notoriously bad factory a/c, but with upgrades it can be improved substantially. Do a search and you'll see some of the clever and effective solutions people have installed. There are LOTS of threads on a/c improvements, including adding barrier hoses. 42 degrees at the vent isn't bad, but you can do better.

HTH.

Scott

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Typical high side pressures (without adjustment for altitude):

For R-12
80 F ambient 170 to 210 psi
85 F ambient 180 to 220 psi
90 F ambient 190 to 230 psi
95 F ambient 205 to 250 psi
100 F ambient 220 to 270 psi

For R-134a
70 to 80 F ambient 115 to 200 psi
80 to 90 F ambient 140 to 235 psi
90 to 100 F ambient 165 to 270 psi
100 to 110 F ambient 210 to 310 psi

Typical low side pressures (not adjusted for altitude):

For R-12
32 F Evaporator temp 30 psi
36 F Evaporator temp 35 psi
42 F Evaporator temp 40 psi
48 F Evaporator temp 45 psi
53 F Evaporator temp 50 psi

For 134a
33-50 F Evaporator temp 16 to 29 psi
33-60 F Evaporator temp 19 to 39 psi
40-65 F Evaporator temp 25 to 43 psi
48-65 F Evaporator temp 37 to 51 psi

[Vmarch]

Those numbers are switched. R-12 systems operate at lower discharge and suction pressures than 134. You have not mentioned whether you are using the stock compresor or a replacement efficiency model. If you have not swtiched out to barrier hoses and a new drier, you might as well give your money to some idiot politician to spend. With a 930, you can put an updated rear condenser, condenser fan and run 134, but keep it stock, it was designed by real German engineers.