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AC question

Discussion in 'The Garage' started by 1977k5, Feb 22, 2007.

  1. 1977k5

    1977k5 3/4 ton status Vendor

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    I replaced the air conditioning condensor on my car and now the system is full of air. I don't have a vacuum pump and the cheapest I can get a local shop to pull the air out is $60 :rolleyes:. How important is it that I get the air out of there? I have heard that the only reason you need to pull the air out is to avoid moisture and contamination (it is very dry here). I really would like to just refill the system and be done with it. TIA
     
  2. HarryH3

    HarryH3 1 ton status Author

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    When I lived in Colorado Springs, I got the guys at the brake place attached to Advance Auto Parts (Brakes Plus, maybe?) to vacuum my system for $25. They just hooked it up and let the pump run for an hour. Then I filled 'er up with r134a myself.
     
  3. sandawgk5

    sandawgk5 3/4 ton status

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    No matter how "dry" the air feels there is still moisture in it. The moisture will combine with the freon and create an acid that will cause corrosion inside the system and it will eat all of the orings. Also even though the can is pressurized you need the extra difference in pressure of the system in a vacuum on top of the can pressure to normally get a full charge in the system.

    Have it evaced and do it right or you will get an opportunity to do it again in about 2 weeks.

    Ira
     
  4. Jason4x4

    Jason4x4 1/2 ton status

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    autozones down here will loan a vacuum pump.
     
  5. 5280k5

    5280k5 1/2 ton status

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    How 'bout we just do it for free! PM'd ya:D
     
  6. K5er4Life

    K5er4Life 1/2 ton status

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    After a vaccum is drawn on the system, besides removing moisture it will make the refridgerant more efficient for the closed system. Vaccum is very important for an extremely effective a/c system. I cant remeber why my book said so exactly and Im too tired to try to think about it and explain. I will look it up later and post what it says exaclty, that is of course if someone beats me to it which would be appreciated.
     
  7. k204dr

    k204dr 1/2 ton status

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    i've used the engine vacuum before when i was real desparate. works pretty good, just kinda goofy to hook it all up.
     
  8. sandawgk5

    sandawgk5 3/4 ton status

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    It has to do with the something called a Mollier diagram. Different fluids boil at different temps these temps change with pressure. Freon works as a refrigerant because R-12 for example boils at 32F. When it boils it is removing heat from the air (almost like evaporation inside the pipe). Now if you raise the pressure in the system the subsequent boiling point will also raise therefore it will no boil at say 45F for instance. You can see how you system would not be as efficient.

    Ira
     

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