2001 FLD 120 AC compressor question

Discussion in 'Freightliner Forum' started by Adamjorgy, Jun 27, 2015.

  1. Adamjorgy

    Adamjorgy Bobtail Member

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    Mar 24, 2015
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    I was getting bad air flow through the vents in my truck so I took the one cold side of the heater core and washed it so I had to take the two free on lines off the heater core so obviously it all drained out.. But once I put it all back together I filled the truck with 3 pounds 7 ounces of free on like I was told and I still can't get my compressor to turn on.. Any ideas?
     
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  3. FuzzFace2

    FuzzFace2 Medium Load Member

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    Jul 27, 2014
    Angier, N.C.
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    Quick & dirty here.

    1 it is against the law to let ANY A/C gas out in the air. You need to re-cover it with a machine, filter it and reuse it.

    2 when a system is open you need to pull a vacuum on it and hold for a min. of 1 hour to make sure you have no leaks.

    3 not knowing how old the system is, the filter/drier should be replaced and expansion valve(s) replaced when open and before pulling a vacuum.

    Once the service has been done and system holds vacuum you should be able to add the gas back to the system using gauges so you know how much is in it. Too little and it will not have psi needed to turn a safety switch on. You don’t want to run a compressor with no gas as it will burn up and no psi means no gas to run. Also if you have enough gas to keep switch closed you freeze up the evap coil and cause damage. There should be a safety switch for this too.

    Too much PSI is not good either as it will not cool as it should but all safety switches would let pump run.

    I would say if you don't have the tools or know how take it to someone that does.
    Dave ----
     
  4. Oscar the KW

    Oscar the KW Going Tarpless

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    You need to have it vacuumed down, otherwise you will end up with moisture in the system that will corrode and destroy componets, costing you more in the long run.
     
  5. Adamjorgy

    Adamjorgy Bobtail Member

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    Mar 24, 2015
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    How much psi should there be on the low side nozzle?
     
  6. KeithT1967

    KeithT1967 Road Train Member

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    Springfield, Ohio
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    R-134 works best in the around 27 psi on the low side. Thats not a hard number though. One of my 4 wheelers refuses to get below 35 and you need arctic gear when its on full.
     
  7. OldHasBeen

    OldHasBeen Road Train Member

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    I've took several a/c apart of my own and never pulled the vacuum on them and never had them freeze up because of moisture, and every one of them blew very cold air.
     
  8. xsetra

    xsetra Road Train Member

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    Problem with the lines going to bunk. The hangers that are coated with rubber to protect the Freon lines will wear holes in them when they get old. The rubber ages and falls off and the metal bracket has direct contact on the lines and that is what happens. Not sure what those lines cost now but 2 years ago they were 200 each from a dealer.
    Also too much Freon In your system will cause your compressor to lock up when the Freon starts to expand and gets to high a pressure.
    R15 and R-25 real freon gas should never be vented to the atmosphere. R-134a The gas used now is not Freon. It is a synthetic substitute.
    http://www.mazergroup.ca/wp-content/uploads/2012/07/MSDS-Dupont-R134a-Refrigerant.pdf
    Good luck.
     
  9. nasriza

    nasriza Road Train Member

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    Chicago, IL
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    when you removed evaporator you should have removed the thermostat or thermosta probe small like a fat match box with long wire running into evaporator fins if this is not plugged in or not back in its proper place you're ac will never turn on
     
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