Ac compressor replacement. ?

Hey I have a question. Ok so I understand the purpose of getting the ac system vaccumed out, but if I the hose that I pulled from the old ac compressor already leaked out all the freon and dried up would I still need to get it vacuumed down if so why? Because I'm thinking I should be good and able to recharge and presto cold air. My issue is my ac compressor is bad and I need to replace it because it's not turning on and I no longer have cold air. So again I wouldnt need to get it vacuumed down correct?

6 Answers

  • 4 months ago

    If you think just breaking a line loose and letting the freon out is the same as evacuating the system, it isn't. You likely let a lot of stuff you don't want in your a/c system in doing that. Best thing to do is hook the lines back up, then vacuum it down. It will also help aid in making it easier to fill back up, as the suction from the negative pressure will pull the pag-oil and freon back in. Make sure you put pag-oil, whatever type you have to put back into the compressor. If you don't you will end up ruining your new compressor.

  • M.
    Lv 7
    4 months ago

    Apparently you DON'T understand the purpose of evacuating the A/C system before charging it with refrigerant.  

    The purpose is to remove all MOISTURE and NON-CONDENSABLE GASSES. 

    The vacuum will also show if there is a leak.  There is no good reason for charging a system that leaks (can't hold vacuum). 

    After you evacuate the system, you charge into the vacuum.  You don't want any AIR in the system.  You need a gauge set and a vacuum pump to charge the system properly, not a can of refrigerant with one gauge and a short hose. 

    Also, when you remove a major part like the compressor or condenser, those parts have refrigeration oil trapped inside.  You must drain the oil and replace at least that amount into the new system so the new compressor gets lubricated properly and continuously.  A new or rebuilt compressor has no refrigeration oil in it.  When operating, the refrigerant constantly moves oil around and lubricates the compressor. 

    If a compressor is replaced due to mechanical failure, you need to open the system and flush out any metal/debris, otherwise the new compressor will have a very short life. 

    You also replace the filter/dryer (because you can't flush it clean). 

    You also make sure the metering device (expansion valve or capillary tube) is not harboring metal/debris. 

    I question WHY you think your compressor needs to be replaced???


    Q:  "So again I wouldnt need to get it vacuumed down correct?" 


    You are not cleaning like you clean the floor with a vacuum cleaner.  You are evacuating the atmosphere inside the A/C system of moisture (humidity) and air (oxygen, nitrogen, et cetera). 

    You show your misunderstanding when you use the term "vacuuming". 

    Instead, use the term "evacuate/evacuating". 

    I don't have the energy to explain the term "Freon®".  Just use the term "refrigerant". 

    -Engine overhaul mechanic and general automotive mechanic since 1972 

    -A/C repair since 1980

  • 4 months ago

    You need to apply a vacuum for a good 20 minutes to get all the air out of the system before charging it with 134a. You're thinking wrong.

  • Anonymous
    4 months ago

    The system may contain no air when it is filled, it must be in vacuum. Air in the system is death.

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  • Anonymous
    4 months ago

    Year make and model.

    "My issue is my ac compressor is bad and I need to replace it because it's not turning on".  That is a very quick and wrong diagnostic check.  Good mechanics never assume.  Check if the clutch is engaging.  If it does not, check if it is getting powered and getting a good ground when the engine is running and the AC is on.  If there is power and good ground, the clutch coil is bad and you need a new clutch coil or compressor.  If it does not have a power and or a good ground, there is an electrical issue or the system is low on charge and a new compressor will not fix the problem.

    And vacuuming is ALWAYS required after replacing a component in the system.

  • Anonymous
    4 months ago

    Good luck with that.

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