A/C refrigerant capacity documented - 1989 911 SC

[heimtun]

So where exactly does one find the specification documentation for refrigerant capacity.
TIA,
Wayne

[DaveMcKenz]

What kind of car?

[Bob Kontak]

On the Carrera's it's clearly labeled on stickers in the engine compartment.

You mention 1989 911 SC. That is not correct. SC's were from 78-83.

What specific car are you looking for with regards to capacity?

To answer you question, it's also available in the factory manuals.

[heimtun]

Originally Posted by Bob Kontak

On the Carrera's it's clearly labeled on stickers in the engine compartment.

You mention 1989 911 SC. That is not correct. SC's were from 78-83.

What specific car are you looking for with regards to capacity?

To answer you question, it's also available in the factory manuals.

Oooops fat fingers 1980 911 SC

[Ronnie's.930]

It's also not necessary to know the capacities, or adhere to them, in order to achieve excellent results (can charge by way of pressures and vent temps).

Written primarily to yank Bob's chain for sport, but true none the less.

[Bob Kontak]

Originally Posted by heimtun

Oooops fat fingers 1980 911 SC

I have it at home in the manuals. I just looked in a book called "Porsche 911, the Essential Companion" "AC refrigerant" , page 77, tells you to use R-12. Oh, thanks.

I will look tonight if I remember.

[DaveMcKenz]

You know, Ronnie and Bob kind of grow on me.
Dave

[Ronnie's.930]

^^^ Ha - too funny!

Speaking of "grow on me", have you seen the troubling fungus type stuff growing on Bob's back and shoulders? I saw pics of it when I stumbled on this website dedicated to bizarre human skin ailments. Poor guy! Maybe he can try hosing himself down with that 30lb tank of R12 he's always crowing about!

[Bob Kontak]

Originally Posted by Ronnie's.930

Speaking of "grow on me", have you seen the troubling fungus type stuff growing on Bob's back and shoulders? I saw pics of it when I stumbled on this website ....................

Same website where it shows the immense suppurative wound in your skull right before you started talking about vent temps being a variable driver in AC diagnosis.

Bring it.

[Ronnie's.930]

Here's a rare video of Bob relaxing after a hard day of ****ing up automotive a/c systems -

[kuehl]

1989, 911, R12, = 47.6 oz

[GH85Carrera]

The factory specified capacity is only relevant if you are going to use R-12 to recharge.

If you are thinking up going to R134A the capacity is much different (less).

[heimtun]

Originally Posted by kuehl

1989, 911, R12, = 47.6 oz

Thanks kuehl... my bad, I mistyped my car's year. It is a 1980.

[Bob Kontak]

Here is a passage I typed up in 2011 from the factory manual. If it's Factory book #2 then that was before the SC. Note the vent temps.

It still does not answer your question.

Originally Posted by Bob Kontak

For the "old" Behr systems that have the square York compressor there is a graph in big book number 2 in the back under Technical Remarks - Accessories. There is a lot of info in there.

At 80 degrees F air entry temp, liquifying pressure range is about 190 to about 225 psi.

Cold air outlet temp 34-41 F until the car has cooled then 36 - 43 F

39 oz entire system capacity

Did not see a low side pressure.

It says you can perform temperature corrections by adjusting the temperature switch set screw. I don't hear this talked about much in threads. Perhaps the is the secret to making the 911 AC systems blow arctic air in Phoenix. :-)

[Bob Kontak]

Originally Posted by GH85Carrera

The factory specified capacity is only relevant if you are going to use R-12 to recharge.

If you are thinking up going to R134A the capacity is much different (less).

Saw from some old posts that R134 is 80-85% of R-12. Don't know if right or wrong.

If I don't know the exact weight, I'll use pressures.

Ronnie says use vent temps but until you know what they should be.........

[Ronnie's.930]

Originally Posted by Bob Kontak

Ronnie says use vent temps but until you know what they should be.........

That's easy, Bob; they should be in a range of cold-to-colder.

[kuehl]

Originally Posted by Bob Kontak

Saw from some old posts that R134 is 80-85% of R-12. Don't know if right or wrong.

..

80-90% is rule of thumb, meaning is a starting point. Final charge is always based
on P&T for the particular refrigerant you are using. However, if for example your stock system says 39 oz of R12, and you got 24 oz of R12 in the system, and your P&T matches the refrigerant chart, then you know you have a problem, such as air in the system. Hence, we always use both P&T and expected final refrigerant weight.. together.

[heimtun]

Originally Posted by kuehl

80-90% is rule of thumb, meaning is a starting point. Final charge is always based
on P&T for the particular refrigerant you are using. However, if for example your stock system says 39 oz of R12, and you got 24 oz of R12 in the system, and your P&T matches the refrigerant chart, then you know you have a problem, such as air in the system. Hence, we always use both P&T and expected final refrigerant weight.. together.

I had mentioned in another thread that put about 34oz of r-134a in a total empty 911SC system with a newish rotary compressor (0 psi on low side engine off).

Some folks said that is should only have been 24oz.

Hence, I created this post to try to get a handle on where I should look for documentation on my car - 1980 911 SC.

For reference, these are the results after charging system with 34 oz of r-134a: low side ~40psi (unknow high side - I don't have a complete manifold) at an outside temp ~78 F.

Three months later: vent temp around 30 f with outside temp in high 80s F.
I like my results - I just don't want to destroy anything.

Wayne

[kuehl]

Wayne,

The problem with the DIY R134a cans with a low side gauge is you can't read the high side; as you noted. If is possible to have the correct final refrigerant charge amount, a good vent temp, reasonable low side, however if there is air in the system your high side pressure will be too high. So, if you want to play with your AC then get a set of gauges, or you could end up toasting that compressor and having to replace it, the drier, and liquid flush the entire system.... that will keep you busy for a weekend for sure.

[heimtun]

Originally Posted by kuehl

Wayne,

The problem with the DIY R134a cans with a low side gauge is you can't read the high side; as you noted. If is possible to have the correct final refrigerant charge amount, a good vent temp, reasonable low side, however if there is air in the system your high side pressure will be too high. So, if you want to play with your AC then get a set of gauges, or you could end up toasting that compressor and having to replace it, the drier, and liquid flush the entire system.... that will keep you busy for a weekend for sure.

Thanks again Kuehl. Just ordered a manifold - so what should the high side pressure be?