r12 r134 retrofit on 79 pontiac formula

igor on Wed March 23, 2016 2:56 AM

hi i retrofit my ac system on my 79 formula
i mfrench so sorry for my poor english

what i did
replaced my drier with a new one compatible with r134
setted my cycling switch to r134 (should be readjust after the r134 charge)
bought r12 r134 hi and low ports adapters with valves inside them
unscrewed the old r 12 schrader valves
replaced the old hoses with barrier hoses
bought green orings
cleaned all the parts with chemical product and air
replaced the old orifice tube by a variable orifice tube
i will use pag46 oil like recommended for my new compressor

i tried to rebuild my a6 compressor with double lips seals like it s explained on your forum but with no success....it still leaks...i think my front axle is used.
so i decided to bought a s6 aluminium replacement one.

my stock system needs 3.75lbs (1.70 kg) of r 12 and 10 ozs of oil.

1. how much oil do i need...considering my new s6 compressor...and a little little bit bigger drier ?
2. i drained the s6 compressor normally delivered witg 220cc of pag46 and found 200cc (around 7.5 ozs).
do i have to refill the rest of oil needed for my system in the compressor or somwhere else ?
3. first time we used a vaccum pump, i have a leak at the r12r134 adapaters ports....i screw them too much...i read it must be screwed by hand...is it true....there is a specific torque ?
4. most of the time i read 80% of r134 in a retrofit. i supposed it s a general rule...but how can i check if i have enough or too much gaz in my system ?

thank you

Dougflas on Thu March 24, 2016 7:35 AM

I would not use a variable orfice tube. They are made for vehicles that operate mostly low speeds lake mail delivery vehicles.

igor on Thu March 24, 2016 8:16 AM

http://www.classicautoair.com/GM_OEM_Parts.html
it s suggested on some website and forums so i trust in people. i don t know if it is really better.
they said it works better with r134 at idle

igor on Thu March 24, 2016 11:41 AM

you re right some people say it could be worst because it s difficult to know wich vov tu use and keep the gm stock orifice tube.

for my question about adapters ports i found 20 ft lbs ..is it correct ?

mk378 on Fri March 25, 2016 8:37 AM

They have rubber seals, so they don't have to be much more than hand tight.

igor on Fri March 25, 2016 2:36 PM

that s the same for all the rest ...all the hoses / lines ?

igor on Fri March 25, 2016 2:38 PM

i ve read a lot about variable and fixed orifice tube....people says it s better some others not.

igor on Mon March 28, 2016 5:44 PM

can you explain why vot could create a problem compared to fixed orifice tube ?

Dougflas on Tue March 29, 2016 6:27 PM

you want to keep the evap flooded. Variable tubes vary the amount of refrigerant. Google is your friend.

TRB on Tue March 29, 2016 8:43 PM

Nothing but issues when we used VOV valves.

Best conversion results will come from upgrading the condenser.

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igor on Wed March 30, 2016 1:19 AM

ok....something else i have a doubt
my stock system needs 10 oz of oil with r12
my new s6 is delivered with aorund 7.5 oz
so i thougt i need to add the rest (2.5 oz) in compressor
but with the conversion and the r134, i will certainly use less gaz compared to r 12
if i used 80% of r12 charge with r134....,do i have to recalculate the quantity of oil....for example 80%ÃÂ10oz =8 oz or stay with the 10oz oil....

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