Freon... How many pounds

Discussion in 'Engine Topic' started by spav350, Jul 8, 2014.

  1. spav350

    spav350 Veteran Member Lifetime Gold Member

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    Does anyone know an estimate on the amount of freon a factory ac '70 would hold? The only difference is i have a sanden compressor which shouldnt effect the volume i wouldnt think.
     
  2. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    2nd Gen Camaro R12 capacity is 52 oz.
     
  3. Damon

    Damon Veteran Member

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    I just keep adding until the compressor will stay running at idle, A/C on full blast, on a hot day. Keep track of how much you're putting in as you go along.

    They didn't put much in these systems. Usually a couple pounds will do it (get it working well enough you will be happy with it). If you're low, you'll notice (compressor cycling excessively). If you're high, you usually won't except it doesn't cool very well and seals can start blowing out.

    I WOULD touch base with Sanden about the amount of oil the system will need. The compressor type can affect the amount of oil needed significantly from stock.
     
    Last edited: Jul 8, 2014
  4. twozs

    twozs Veteran Member

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    12 or 134 as 134 should be reduced by 20 % . Don't forget the correct oil . Anyway does your car have a sight glass on the accumulator ? If it does , you can charge that way .
     
    Last edited: Jul 8, 2014
  5. spav350

    spav350 Veteran Member Lifetime Gold Member

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    I converted to 134a. Had the poa rebuilt and recald all new lines new condensor original evap new x valve new drier (with sight glass). I have it currently running with no high psi or low psi switches. With that the elctric fan controller from flexilite turns the fans on a low percentage while the comp is engaged. So while the comp is engaged the fans are on low. So far ive put what i believe is entirely too much in it. At idle the system is running high side 225-250 low at 30-35. Cools great with no air bubbles in the sight glass at idle. When cruising it stops cooling. I have 4-1/2 cans in there now. Ive worked on numerous ac systems on cars and trucks, and can diagnos a problem pretty well, but the electric fan i believe is throwing me for a loop. I believe i have it in my head i need 225-250 at idle to be cool but in reality i need to be lower as the rpms raise so does my psi but not the fan speed. Make any sense? Any other thoughts other than way too much freon?
     
  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Should be about 42 oz of R134a.

    I think you've got it overcharged.
     
  7. B2inSC

    B2inSC Veteran Member

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    Your system is overcharged. If you are running the POA and it has been regulated to run 134a, you should be around 27-29 psi on the low side...or possibly a bit lower even. There is nothing wrong with running a sanden style compressor with an otherwise stock system including the POA valve. It wasn't designed to "cycle". These systems should have the compressor engaged the entire time the AC is turned on. The only thing you might could change to get better performance is the condensor....key word, MIGHT. I have essentially the same setup you have in a 70 Camaro. It is a factory AC car and I'm running all factory parts except for compressor and condensor. I have a sanden compressor and used a parallell flow condensor since the factory one on my car was long gone. I have a factory style clutch fan with a new clutch. I calibrated a factory POA valve to work best with R134a. This thing blows ice cubes. Idle, cruise. Doens't matter. It is very cold and does so with relatively low psi numbers on the low and high side. I used three total cans of R134a to charge the system. As I charged, I monitored vent temps. By can number three, my vent temps were a little below 40 degrees at idle. I've never touched it since.

    Edit: These factory POA systems will not mirror numbers recommended on charging "charts" for 134a on the low side. What you'll need is quite a bit less than what is common on factory 134a cycling systems.
     
    Last edited: Jul 9, 2014
  8. hhott71

    hhott71 R.I.P 11/19/18 Lifetime Gold Member

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    Since you are using the Sanden Compressor. I'd advise getting a new parallel condenser also to work with R134a better in high heat slow speed traffic.

    I would start at 36 oz of R134a. It is far easier to add freon then to precisely remove some.

    New drier is a must.
    Flush the Evaporator and POA. A newr expansion valve won't hurt but the OE will work fine.
    Remove the old valve cores when adding the R134a charge fittings.
     
  9. spav350

    spav350 Veteran Member Lifetime Gold Member

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    So I'm really not too much over. I'm going recover a little and see how she does. Thanks everyone!
     
  10. hhott71

    hhott71 R.I.P 11/19/18 Lifetime Gold Member

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    There should be a stream of bubbles in your sightglass with R134a.
     

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