Volvo vnl AC problem, charging the system properly?

Discussion in 'Volvo Forum' started by Jack carg, Apr 23, 2019.

  1. Jack carg

    Jack carg Bobtail Member

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    Hi guys
    I have problem with my AC , it's was leaking from the expansion valve I replace the part and stop leaking , now I tried to charge the system but when I turn the AC ON it goes to low pressure 10psi and when I turn it OF it's goes to full more than 40psi

    I put abute 15 ounces , how many ounces I need to charge the system? was full Empty

    2015 d13 vnl670
    Any idea can help please
     

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    Last edited: Apr 23, 2019
  2. rhitrucking

    rhitrucking Light Load Member

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  3. Intothesunset

    Intothesunset Medium Load Member

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    You need to go to a shop. And get Vacuum pressurized.
    Watch what they do.
    Do not over fill your AC system.
     
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  4. Jack carg

    Jack carg Bobtail Member

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    Rideandrepair Thanks this.
  5. Jack carg

    Jack carg Bobtail Member

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    Thank you
    Yes I understand, its will be big problem if the system got overcharge
     
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  6. rhitrucking

    rhitrucking Light Load Member

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    The system should be vacuumed to get out all the moisture prior to filling though.
     
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  7. Rideandrepair

    Rideandrepair Road Train Member

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    That’s normal. Gauge always does that when filling system. If overfilled ( assuming high pressure switch is good) compressor will stay cycled off longer than it stays on, overfilled more it will cycle on and off rapidly, fill it some more and it will cycle off and stay off.A good number if not sure on amount is 35 lbs. Best to not run it too long without properly pulling a vacuum to eliminate moisture, and refilling it. $25 air drier while your at it. Otherwise rust will form and you’ll end up replacing expansion valves again.
     
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  8. miszel

    miszel Light Load Member

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    Don't forget you need to add peg oil otherwise you will be buying a compressor in few months
     
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  9. KB3MMX

    KB3MMX Road Train Member

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    Not for just a recharge, it'll have too much oil
     
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  10. Rideandrepair

    Rideandrepair Road Train Member

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    One thing I learned the last time I re did my system is. It’s actually better according to Compressor manufacturer ( Sanden) to be a little low on oil than too much. Too much will displace the gas and cause compressor to run hot. The compressor relies on the refrigerant for cooling. Surprised Me as I used to always put a little extra, for bearings I figured. They have different guidelines on their website for how much oil to add for each failure, hose, condenser etc. For compressor replacement they actually say to dump oil out of new compressor and old compressor and the amount that the old one had to the new one. Most of the oil stays in the system, mostly just gas leaks out.. I just got mine fixed. New condensor. Also had a bad low pressure switch, got it jumped now. Then had a loose hose connection, as I was being careful not to break the new one. Finally got cold air as of now. Gonna slap one more can for good luck. When I get home I’ll pull a vacuum and replace drier and put in exactly 5 cans. I’m good to go. Good luck with yours
     
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