Updating A6 compressor to 134A

Discussion in 'The Big Chill' started by Dr. Roger, Jul 20, 2018.

  1. Dr. Roger

    Dr. Roger Stock enthusiast

    I am restoring the AC on my GS. It was an original AC car. I dug through Mike Garrison's skylark graveyard a couple years ago and and got all the missing components. Got the condenser/evaporator cleaned out and pressure tested, new expansion valve, 134a dryer, replaced all the seals with green seals, etc. I was wanting to go back to the factory A6 compressor and upgrade to R134A.

    Some folks tell me the A6 with 134A won't cool down the car and others tell me it works fine. I've also heard it will work best if only charged to 80% with 134A.

    Anyone run 134A in an A6 compressor? How does it perform?

  2. Briz

    Briz Platinum Level Contributor

    Id not bother with the A6. You'll still have that annoying front seal leak and the oil slinging under the hood. Spend the $ and get the Progen6 compressor. Direct replacement. Draws less power to run and no leaks.
  3. 69a-body

    69a-body Well-Known Member

    Ok fwiw.. Concerning the leaky a6 seal.. I've read the solution is the double lip seal from a r4 compressor.

    The not cooling with 134a . you really need a 20% larger preferably parallel flow condenser. It's not as effective as r12 . pressure curves and calibration different . To optimize it needs different orifice tube,expansion valve or poa adjustment.

    Read up on dust off r152a as a refrigerant.. It's molecular weight is higher and takes a lot less charge, has lower pressures, and rivals r12 in thermal capacity
  4. 455monte

    455monte Well-Known Member

    I converted my 67 to 134a
    Blows 37 degrees with a original a6 compressor.
    I recalibrated poa valve using info from a corvette forum.
    Used all new orings with original hoses and condensor.
    After 2 years i had to add 1 12 oz can of freon.
    Ive heard the original 12 hoses and a6 ceramic seals do seep. But for 4.88 a can at wally world im good with it.
  5. Dr. Roger

    Dr. Roger Stock enthusiast

    455Monte; Do you fully charge it when you recharge the system?
    I was planning on ordering a re-calibrated POA valve. If I remember right, you have to cut the POA valve open to re-calibrate, which sounds like a can of worms.
    I don't mind recharging it occasionally since the refrigerant costs about as much as a liter of Pepsi. Heat index yesterday was 120 degrees, so AC is essential.
  6. philbquick

    philbquick Founders Club Member

    They sell POA and expansion valves calibrated for R134. There's 2 other options for the expansion valve 1) gut the stock expansion valve and drop a variable orifice tube into the evaporator. Be sure to dimple the evaporator input tube about an inch from the end so the orifice tube doesn't fall all the way in. This option costs about $12 and is well worth it, be sure to use a variable orifice tube not a fixed one. https://www.ebay.com/itm/Smart-VOV-...rfice+tube&_from=R40&rt=nc&_trksid=m570.l1313

    2) you can recalibrate your stock expansion valve by turing the adjustment clockwise until it bottoms out while you count the turns. Multiply the number of turns by .6 and back it out that number of turns. For example, if you count 7.5 turns you would need to back out the adjustment 4.5 turns (7.5 X .6 = 4,5).

    I don't know an easy way to re calibrate the POA valve so you'll need to buy that. I ran R134 in my 72 C10 for 7 years with a modified expansion valve and non-modified POA valve and it worked well. It did freeze up the evaporator on long trips, but the POA probably would have fixed that. I could have also fixed it by adding a thermal switch to the evaporator case like GM did in the mid 70s. I replaced hoses as part of the conversion and never added refrigerant during the 7 years.
  7. 455monte

    455monte Well-Known Member

    The poa isnt hard to calibrate.
    I run a stock replacment expansion valve.
    I used the pressure regulator on my air conpressor to limit prrssure and adapted it to the poa.
    Used my ac gauge set to monitor the flow psi to get to correct psi for 134a freon.
    Seems like i had to turn the nut inside the poa approx 3/4 a turn.
    Let me see if i can find the info to give u correct psi numbers for both refridgerants
  8. 455monte

    455monte Well-Known Member

  9. Dr. Roger

    Dr. Roger Stock enthusiast

    I installed a new OEM-style expansion valve (Autozone ~ $20) says "use with R12/134a." I assume it is plug-and-play. Guess I should check and see if it needs adjustment.

    Only nut I see in the POA valve is very small (less than 1/4 inch wide) nut when you look into the end. I will definitely need to flush out the old POA valve as it full of dried up r12 oil.
  10. Dr. Roger

    Dr. Roger Stock enthusiast

    Here is a picture of the only nut I find in the POA valve.
  11. Mopar

    Mopar Well-Known Member

    Could you not just use 12a?
  12. Dr. Roger

    Dr. Roger Stock enthusiast

    I want to steer clear of flammable gasses and use the "standard." That way, the next person that owns it will know what to expect when they work on it (or the technician that recharges their system).

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