72 SunCoupe a/c

Discussion in 'The Big Chill' started by 36racin, Oct 9, 2017.

  1. 36racin

    36racin Platinum Level Contributor

    Been working to get the stock a/c system going again on my SunCoupe. Purchased car with non-working a/c. Did a complete flush of all components except the compressor. Replaced every oring with new. Pressure tested with nitrogen to 110psi with snoop and found several leaks. Replace the liquid line from the expansion valve to the dryer(major leak). Someone had tried to overtighten this fitting and tore the flanged area off the hose and the oring had no where to sit against. Pulled a vacuum to 28" and it only slightly lost pressure overnight. Was told the a-6 compressor seal is probably leaking and to charge system(134a) and get oil circulating and see what happens. Did that yesterday evening and started the system. Had to jump the compressor to get it to work. Looks line the thermal fuse may be bad. With system running it is only cooling to around 60* with a/c on max. Looking at the inspection window on the dryer and it looks like foam in the window. How much Freon do these systems take? What kind of pressures should I be seeing?
  2. 36racin

    36racin Platinum Level Contributor

    So I checked the thermal fuse and it's ok. Maybe I didn't have enough 134a Freon in system to get the pressure up enough to run the system normally. Chassis manual says(just found) 3 3/4 or 4 1/2 pounds. That would be the R-12 Freon. I'm at just over two pounds(3) 12 oz can right now. Just don't want to overfill system. Seems like I read somewhere I needed more 134a than R12. Not sure about that though. So before I add more Freon I'd like some opinions

  3. musclecarz

    musclecarz Well-Known Member

    For 134a, 80% of the r12 charge which is 3.75lbs. That comes out to 3lbs. Did you recalibrate the poa valve? System would also really benefit from a parallel flow condenser. You don't look at the sightglass when charging with 134a. I'm willing to bet you are gonna leak out the front of the shaft seal if that's the original compressor as pressures are higher on 134a. I would swap in a double lip shaft seal to help with this
  4. 36racin

    36racin Platinum Level Contributor

    So as of now I'm at 3lbs of 134a and holding around 55 degrees coming out of the center ac vent on recirc and max. I did not recalibrate the POA valve yet. When I started this I wanted a/c for a week long car show incase I needed the defrost or it was raining. I did put die into the system so I can find the leaks if they reappear. I was told to make sure I run the ac system weekly if I still had the A-6 compressor, which I do. I had planned all along if the system leaked too bad to replace everything. New Pro6ten compressor, new parallel condenser, recalibrated POA and what ever else was needed. One note is I can't get discharge pressure with the 134 fitting on the compressor. I need to find some r-12 gauges and try to get a discharge pressure reading.
  5. TexasT

    TexasT Texas, where are you from

    I bought some fittings of the eBay to convert the 134a gauge hose to the r12 fitting on my Regal. Like $6 ea I think.

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