Recharge issue

Discussion in 'The Big Chill' started by Robroy455, Jun 12, 2019.

  1. Robroy455

    Robroy455 Well-Known Member

    Issue:
    AC compressor running but the recharge was going real slow or not at all and almost no cooling although system fully recharged with 4 lbs (1.8 kg)

    Background:
    Last summer I had the AC recharged on my 73, we started by evacuating the system as it had been empty for a 2-3 years and could then also see that it was not 100% tight as expected.
    My friend who helped me thought we should give it a shot anyway and charge up the system as exercising it might fresh up the sealings, a long-shot but worth a try.

    And so we did the and I had excellent cooling for about two months, then it faded and finally stopped working at all, as before the recharge.

    As we had put in a leak detector liquid, I found a leak at the rear end of the compressor which showed to be a bad o-ring on the Super Heat switch that I later replaced.

    Yesterday I was back at my friends place again and as last time we started by evacuating the system which this time was tight :).

    Then we started the recharge, as last time we had to bypass the thermal limiter switch to get the compressor running which I thought was odd as that component was recently replaced, but today's made in china crap sometimes brakes down directly, or could it be something else causing this?

    Then it started to get really odd; although the compressor was running the recharge was real slow, the refrigerant almost seemed to almost bounce back into the can.
    I took us hours, but we finally got in the system fully charged up, but no real cooling to talk about, very far from the result last time, what could be wrong?
    Any ideas? appreciate any hint or lead...
     
  2. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    I assume that it being a 73 it has the V.I.R. assembly ??? It was only used a couple of years and then GM ditched it. I had one that had good pressures on both sides but wouldn't cool and was hard to fill in the first place .Maybe someone expieranced can chime in .
     
  3. Robroy455

    Robroy455 Well-Known Member

    thanks for the reply gsx455-4ever

    Assume this could be the V.I:R assembly?

    Btw forgot to mention that the aluminium pipe on top of the compressor get frosty cold as it usual does when you have the ac on, although no cool effect inside the car
     

    Attached Files:

  4. telriv

    telriv Well-Known Member

    Being low on Freon ALSO makes the pipe frosty.
     
  5. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    Can you tell us the pressures on the High side and the Low side ?? I guess you are still using R12 ?? One thing I can tell you is DON"T get a VIR assembly from the AC people in Texas. .
     
  6. Redmanf1

    Redmanf1 Gold Level Contributor

    You could have an ac orifice tube clogged
     
  7. Robroy455

    Robroy455 Well-Known Member

    We use the good ol stuff yes

    I have one of those cheap recharge hoses with manometer included that I think I might be able to use if I hook it up to an empty can, that could work to measure the pressure on the low side.
    Could also be interesting to see the difference in the low pressure with engine (compressor) on or off

    For the high side I need to either lend a proper manometer or turn to a specialist


    I also thought about if anything has come loose when we were evacuating that then blocked the system somewhere….
     
  8. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    I don't believe the VIR system has a Orifice tube. That would be in mid 70's GM cars.
     
    1973gs likes this.
  9. Robroy455

    Robroy455 Well-Known Member

    Good, then we probably can exclude that one as a cause...:)
     
  10. Robroy455

    Robroy455 Well-Known Member

    Measured the pressure on the low side this weekend and when I first hooked up the gauge I got 1.6kg which then got down to 1.0 kg and stayed there.

    It’s too low (should be around 2.0) I know which is odd because we have put in 1.8 kg in weight having the can (different equipment than on the pict) on a scale when we were doing the recharge.

    But then either the gauge or scale could be slightly faulty, will try to get a shop to do a proper measure on both low and high side
     

    Attached Files:

    Last edited: Jun 17, 2019
  11. 1973gs

    1973gs Well-Known Member

    Need to know high and low side pressures. It looks like you're using R134. What did you do to convert from R12? What type of oil and how much are you using? You said that you used 4lbs. What is the factory charge for your car using R12?
     
  12. Robroy455

    Robroy455 Well-Known Member

    Only have the pressure on the low side available at the moment which is 1.0 kg/cm2 (14 psi).

    We have used the kind of cooling refrigerant the car once was designed for, so no R134 and no conversion except the retrofit charge connection.

    My friend that helped me with the recharge has the kind of equipment that blends in the right amount of oil, I believe its called Ester oil

    According to my 73 Buick workshop manual (from 1973) the correct amount of refrigerant to put in is 4 lbs (1.8 kg).
     
  13. Robroy455

    Robroy455 Well-Known Member

    My own conclusion is that I am simply too low on refrigerant based on the low side too low pressure (1.0 kg/cm2 with compressor ON and 5.0 kg/cm2 with OFF, been told those numbers should be around 2 and 7) and that I have a little cooling inside the car with the AC on.

    Could be that the scale under the can was faulty someway as it indicated us having charged 4 lbs (1.8 kg) into the car.

    Then regarding the superslow recharge I was thinking that it might be that the pressure in the can was too low, it seemed to speed up at the end when we lifted the can at a higher level than the car, also remember he mentioned that the can was getting close to empty.

    If I’m right it could explain why we had such success last year with recharge using the exact same equipment on the same car.
     
  14. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    Per . I had to get a conversion scale to convert Kg/CM to PSI and I would say you are low on refrigerant. . I would add until I saw around 30 PSI ( Appx. 2 Kg/CM2 ) on the low side and around 200 PSI ( Appx. 16 Kg / CM2 ) on the high side while running and see what the temperature is coming out of the vents inside the car . Check my conversion #'s .

    While OFF I would expect to see 75-90 PSI ( 5 Kg/CM2 to appx. 6 Kg/CM2 )

    Check my conversions as We here in the States are not used to the Metric system . I can get the length and Weight measurements pretty good but I never really grasped the Pressure Measurements .

    There is also a "Sight Glass on the side of the VIR assembly that you could watch till there were no bubbles but I would still monitor pressures and air out let temperature while filling that way . Those old A6 compressors could take a lot of pressure especially on a very hot day 95* F and above . I would not be scared to see over 300 PSI on the high side . I think the shop manual even has a chart to guide you .

    Hope this helps . Let us know how you make out
     
  15. Robroy455

    Robroy455 Well-Known Member

    Thanks for the response gsx455-4ever

    Having worked with a company in the Carolinas for many years I know all about the metric struggle on your side of the pond, but your numbers looks just fine :)

    I recommend using this site that pretty much convert any unit https://www.digitaldutch.com/unitconverter/mass.htm


    Agree that a lot points to I’m too low on refrigerant

    We will give it another shot but the main question still is why it was that hard for the car to take in refrigerant, I’ve been told that the pressure in the can needs to be at least 7 psi higher than in the car to be able to create a flow, so if it was too low in the can it would explain everything

    I’ll keep you updated how it continues
     
  16. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    Years ago they used to have a "Heating Blanket " that wrapped around the can of Freon. It would warm up the can and raise the pressure inside to help dispense the Freon . Are you using a 30 LB can of Freon ?? Sorry I meant to say are you using a 13.6078 Kg can of Freon ? lol . I would try a heating blanket on the can and have the can valve down for Liquid .

    Add a little at a time. I rely on the pressure gauges and outlet temperature more than what the scale weight says . Keep us informed
     
  17. Robroy455

    Robroy455 Well-Known Member

    Hey, using a heating blanket is an excellent idea, thanks so much!

    A colleague suggested a gas welding flame (with an evil smile on his face :D) to heat up the can which seemed like a lot riskier business


    Totally with you regarding having the pressure as a first-hand reference rather than the weight

    It will be another week before we get the chance to try again, but promise to keep you posted
     
  18. Robroy455

    Robroy455 Well-Known Member

    Went to my friend yesterday to do a second recharge attempt.

    On the way going there I turned on the ac but quickly turned it off again as there was a long, loud belt scream the moment I turned it on, then stopped down the road and popped the hood and turned it on again, but this time everything was normal with the compressor running and half-cold air started to come out the vents.

    Arriving at my friends place we topped up with refrigerant reaching 28-29 Psi on the low-pressure side (was 15 Psi before), and the ac now delivered pretty good cooling.
    This time the car took in the refrigerant in lot more normal way, using a fresh can indicates it may have been too low pressure in the one we used last time that was at least part of the problem.

    On my way home again the cooling improved even more and was now more like the last time I had it charged up, but I thought myself hearing a bit of low grinding noise with the ac on, but I wasn’t 100% sure if it was me listening too much (you know how it is :)).

    For a while I was a very happy camper but when testing the ac again on the evening the compressor instantly jammed/stalled with a screaming belt every time I turned it on.

    Checked the belt; tension was good and so far not particularly blank surface on the sides, what I didn’t check was how deep it was in the pulley and if being blank at the bottom.

    So my only hope now is that the belt has reached the bottom of the pulley being worn down to be too narrow, if not I suspect my compressor is toast :(.
     
  19. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Overfilling can cause the compressor to lock up, too.
     
    1973gs likes this.
  20. Robroy455

    Robroy455 Well-Known Member

    Hi Adam

    That’s for sure an interesting input, what little speaks against it in my case is the fact that I got a jam already with only 15 Psi (on the low side) which indicates approximately half-full if I got it right, that is IF you can trust the low side pressure as a filling indicator?

    I read in the buick workshop manual that it was not unusual with a compressor jam at start up of the AC if the system had been out of use for longer times, this due to that the oil took some time to circulate and reach the compressor, in my case it has been out of use for longer times but probably still a long shot, but good to know.

    Previous owner left a large number of belts in the trunk and I found one Gates 9433777 / 7619 dim: 13/32" x 62-5/8 that looks like right length, about .1 mm wider and deeper.
    Gone test that and clean up the pulleys while at it.

    Then if I can somehow get the possibility to measure the pressure on the high side too just to see
     

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