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AC clutch cycling off and on

Discussion in '6.9L IH & 7.3L IDI Diesels' started by rewbrooks50, Oct 15, 2019.

  1. rewbrooks50

    rewbrooks50 Full Access Member

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    1994 F250 IDIT. Flushed the system with ac flush and compressed air. Pulled a vacuum. Replace the ac compressor, orifice filter and dryer. Charge the system with oil.

    Compressor clutch is still cycling on/off.

    57F87C32-92AC-4884-B2F7-7E6C1AC4EC59.jpeg
    What do I do next?
     
  2. Kizer

    Kizer Supporting Member Supporting Member

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    How many cans / lbs. of refrigerant did you use?
     
  3. 79jasper

    79jasper Chickenhawk

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    Cycling usually means low on charge.
    But it could be one of the switches.

    Sent from my SM-N960U using Tapatalk
     
  4. rewbrooks50

    rewbrooks50 Full Access Member

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    I put at least 4 cans Freon, leak dye, and 6 oz of oil. I replaced the low pressure switch. If I jump it the clutch will run full time. I can’t get more Freon in the system. Shouldn’t the low pressure be about 30 not 100 and high about 100.
     
  5. Kizer

    Kizer Supporting Member Supporting Member

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    upload_2019-10-15_11-59-45.png
     
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  6. Kizer

    Kizer Supporting Member Supporting Member

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    You may have gone a little "heavy" on the oil ... by the way.
     
  7. franklin2

    franklin2 Full Access Member

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    When the
    Those pressures are with the clutch off correct? The pressures will equalize in the system with the compressor off. When the compressor kicks on, the pressure should drop. What is the pressure reading when the clutch cycles? It should be around 20 psi or less. What is your high side pressure when the switch cuts off?

    Your pressures will depend on how hot it is inside the cab and outside. If you have a very cool day, your pressures will be low and it will tend to cycle on and off. But the air coming out of the vents should be cool. On a nice hot 90 degree day with lots of hot air going through the coil in the firewall, your low pressure will be 30-40 psi, and your high pressure will be around 250 or so.
     
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  8. dgr

    dgr Full Access Member

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    The clutch is supposed to turn on and off. Is it fast cycling or just doing it's thing? What is the range of pressure on the low side and high side when it's running and your air temperature?
     
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  9. chris142

    chris142 Full Access Member

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    No. He is under oiled. A r134a system requires 3.5oz of oil per pound of r134a.
     
  10. Kizer

    Kizer Supporting Member Supporting Member

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    10-4. I remembered it being 1.5 oz. I should have looked before I said that.
     
  11. rewbrooks50

    rewbrooks50 Full Access Member

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    Finally got enough Freon in. My Harbor Freight gauges was restricting input.
    AC blowing cold now.

    Thanks for all the replies
     
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