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Aircon Gas volume / pressure question

sidibear Aug 19, 2020

  1. sidibear

    sidibear Going with the flow. Staff Member Moderator

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    So, I know it has to have the correct amount at the right pressure. But if the compressor was changed does it need more refrigerant to allow for what is inside the compressor ?
     
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  3. rum4mo

    rum4mo Registered User

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    If when a compressor is replaced, the system is always evacuated, then pressure and vacuum tested after closing the system back up, and then, recharged with the correct weight of fridge gas, and the oil weight that was in the original compressor should have been weighed, then the new compressor's oil content corrected to be the same as the old one.
    Then the system should be run to check for operation, not just for cooling performance, but also to monitor/check Hi side and Lo side running pressures, cooling fan operation etc.

    Edit:- please understand that the fridge circuit is not charged up to a certain pressure, this gas is a relatively low pressure product, so as long as there is any liquid refrigerant in the system, with the engine not running, the system pressure will always be the same but vary with ambient temperature. If the system pressure rises under that set of conditions, some of the gas or saturated refrigerant will turn into liquid again.

    System running pressures will vary with thermal load and the weight of refrigerant loaded into the system, too much refrigerant loaded in will end up with running high side pressure to be above spec and the pressure sensor will inhibit the chilling function.
     
    Last edited: Aug 31, 2020
    sidibear likes this.
  4. sidibear

    sidibear Going with the flow. Staff Member Moderator

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    Excellent, thank you. Compressor has been changed, pressure switch changed and it still don't work. The econ light takes longer to come on than before the compressor was changed. Before it came on straight away, now it takes about 4 seconds, hence I was thinking it may be low on gas.
    Any suggestions are greatly accepted.
     
  5. rum4mo

    rum4mo Registered User

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    Have you checked the operation of the cooling fan, maybe check that and if not running when the AC is switched on, work out a way to check the cooling fan motor and if it is okay connect it directly via a fuse to the battery and if it runs probably at its fast speed, then switch the AC on and see if it stays on, if so, there will be a problem somewhere in the fan control system.
     
  6. sidibear

    sidibear Going with the flow. Staff Member Moderator

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    The problem is that the A/C won't switch on, the econ light is constantly on. I can push the auto switch but as soon as I let it go the econ light comes back on.
     
  7. rum4mo

    rum4mo Registered User

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    You will now need to get the stored fault codes read in the A/C controller, that should be your next move as guessing is not clever.
     
  8. sidibear

    sidibear Going with the flow. Staff Member Moderator

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    That will be my next move. I will try to find someone on here first before booking it in at the local indy.
     

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