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A/C on and off

Discussion in 'Civic and del Sol - EG and EK' started by john07ex, May 7, 2007.

  1. john07ex

    john07ex New Member

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    On My stock 94 civic DX the air conditioner works great unless i turn the fan on higher than 2 it will cut on and off and blow hot.

    If i leave the fan on 1 or 2 it will continue to run all day.

    Any ideas? I checked and the freon level is good?
    the a/c condenser fan does work also.
     
  2. onesikdb8

    onesikdb8 Member

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    Could be your pressure switch or your expansion valve.
     
  3. john07ex

    john07ex New Member

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    Where would that be? Are they expensive and would i need to recharge the system to change it?
     
  4. onesikdb8

    onesikdb8 Member

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    You would need to evacuate the system first. The pressure switch I think is 35-50 from the dealer. I don't remember how much the expansion valve is. After you replace them, you'll need to do a vacuum and then charge the system.
     
  5. civicious

    civicious FüK-VTEC VIP

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    The pressure switch or expansion valve would not cause the A/C to work on some fan settings and not work on others. Either of those would cause the A/C not to cool regardless of your fan settings. You can replace the expansion valve and/or pressure switch if you like, but it isn't going to fix your problem.

    More than likely the problem is in your climate control unit (the thing in your dash that you use to select hot/cold and ac/defrost/heat/whatever). Your best bet would be to replace that, you can probably find another one in a junkyard for fairly cheap.
     
  6. john07ex

    john07ex New Member

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    Ok i would think it was the switch to but if i have it on say 4 it will work.. it just randomly turns on and off unless i stay on fan 2 or 1...?
    so i can run on fan 3 sometimes fine and others it just doesnt cool on 3..
     
  7. civicious

    civicious FüK-VTEC VIP

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    You can replace what you want, I'm just telling you that replacing the pressure switch or the expansion valve is not going to fix your problem.

    A pressure switch failing would cause you to have no A/C at all, regardless of the setting that your fan is on. All the pressure switch does is let your ECU know the pressure of the refrigerant so that it can engage or disengage your compressor clutch. If the pressure switch is bad, your compressor would not engage AT ALL, and you wouldn't get any cool air at all.

    Your expansion valve changes the refrigerant in the A/C lines from high pressure liquid to low pressure liquid before it gets to the evaporator, and just like the pressure switch, if it goes bad you get NO a/c at all. NOT intermittent A/C.

    Also, what setting your fan is on has NO relation WHATSOEVER to the actual A/C system, as far as the components go. As long as you have your A/C on, your A/C system is cooling at a certain temperature regardless of what your fan speed is. In an ideal scenario, the only thing that changes when you change the fan setting is the speed at which the cooled air is blown out of your vents. Whether your fan is set at 1,2,3, or 4, the temperature in your evaporator core is the same.

    My guess as to what's happening is something is shorting out in your control head, and causing either your fan to cut off or your hot/cool blend door to open (and thus allowing warm air into your cooling ducts).

    I can promise you that if the A/C works on some fan settings and doesn't work on others, that it is NOT the expansion valve or the pressure switch.


    But what do I know, I'm just an ASE certified driveability tech.
     
  8. john07ex

    john07ex New Member

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    No thank you very much. I know the working of an A/C system but very little.
    I do appreciate you trying to help. I will swap out the controls and see if it fixes it and let you know..
    :D
    again THANK YOU.. for explaining it better.
     
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