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Ac gauge readings??? What should they read?

Discussion in 'How To Section' started by 01exp4x4, Jul 7, 2012.

  1. 01exp4x4

    01exp4x4 Full Access Members

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    Hi,
    I bought a set of ac gauges and hooked the up to the expy.

    What should they read on a 01 ford with dual air?

    What is the low pressure side suppose to read?

    What is the high pressure side suppose to read?

    At 100 degrees outside and 60% humidity, the low reads 60 psi and the high side reads 250 psi...

    I have the truck at idle when reading.

    Shoul I adjust to 1500 rpm first?

    Ambient presure is 125 on both sides.

    Thanks if you know.... :):drool:
     
  2. stamp11127

    stamp11127 Super Moderator Staff Member

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    From CSG Network:

    R134a Refrigerant Pressure Temperature Calculator

    Static pressure is fine for the outside temp. Low side is high from what I normally run @34-37. The high usually runs between 150-200 but systems vary so these numbers are only guidelines. How well does the system work?

    Dual air really doesn't matter to the system other than having more parts and total amount of refrigerant. Pressure check is at idle.

    More info on mobile a/c, download the study manual:
    MACS | Section 609 Certification

    I have a leak in my system - here are my current readings after refill & die injection this morning:
    Outside temp 78
    Static press: 70 system is slightly low for outside temp
    Lowside press: 37
    Highside press: 170
    Accumulator temp: 46
    Condenser temp: 125

    I edited the numbers after the system equalized, its frosty in there now....
     
    Last edited: Jul 8, 2012
  3. 01exp4x4

    01exp4x4 Full Access Members

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    The system gets cold after its running for a while.

    It used to get cold right away... So something has changed.

    Like you said, my system is running higher than your numbers.

    Perhaps I have to much refrigerant in it?
    Or is it a sign of a bad expansion valve?
    Or is the compressor going bad? - I visually saw it stop and start several times...
    But Have not seen it repeat since.

    I'll check out you link. Thanks.

    By the way, how are you getting your tempature readings? What are you using?
     
  4. stamp11127

    stamp11127 Super Moderator Staff Member

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    I'm using an infrared laser temp gun to get the temps. If there is too much r134a in the system the cooling goes to hell in a hurry and you will also have high pressure on both sides. If there is still air in the system the pressures are higher than normal and out of "balance".

    What amount of r134a did you add?
    How long was the vacuum on the system? - very important step here - can never go to long
    How deep of a vacuum did you pull? r134a requires 29"hg

    Don't start guessing at what is wrong, easier to find out what the problem is then fix it.

    Hook your gauges back up and watch the pressure as it is running. Make note of the lowest low side pressure and the high side pressure when the compressor cuts out.
     
    Last edited: Jul 8, 2012
  5. 01exp4x4

    01exp4x4 Full Access Members

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    Well, thats some good advise, I can tell.
    And to be honest, my ac wasn't getting cool so I added a small can and 1/2 of freon from auto-zone with the small gauge that came with it.

    Well, that may have been the start of my problem.
    I did not take readings with the real gauges before I did that.

    I though that maybe it was low and a can would make it work.

    So, I don't know how much is in there. I never weighed it.
    I never pulled the presure out with a vacuum pump either.

    I have a vacuum pump
    I was going to buy a scale so I could accurately weigh and add the proper amount of freon to the system from a large industrial size canaster of freon I can get my hands on. (not the small auto-zone cans)

    HERE IS MY REAL DELEMA:
    I have a FORD warranty.
    $100 deductable.
    If the compressor has a problem, or the evaporators are clogged etc. They will replace the parts and freon.

    Did I add too much freon?

    I was having the problem before I added it.

    Should I let out gas until the gauges read 35 and 200?

    I want to take it to the dealer with the correct anount in it. And let them pay for the parts and freon...
     
  6. stamp11127

    stamp11127 Super Moderator Staff Member

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    In order to find out what the original problem was, the system needs to be returned to factory specs. The dealer will have a recycling machine that will remove the r134a, pull a vac, test for leaks, then recharge the system. You can do the same thing manually, difference is you release the refrigerant into the air, they don't.
    Usual problems at this age are leaks and worn out compressors. Seeing that yours gets 250 on the high side, it produces good pressure but may also leak over to the low side. You don't know yet since you don't know how much is in the system.
    Once everything is back to spec then your able to get an accurate diagnosis.

    Your call on whether to let the dealer have at it. I don't go to dealers unless absolutely necessary - have only met a few mechs that are competent, the rest only throw parts at the problem. Diagnosis is a disappearing art today.

    You may have air in the system that is contaminating the refrigerant. Reducing the refrigerant level may improve the cooling some but not to what it should be. If you decide to work on it yourself, are you familiar with the procedure?
     
    Last edited: Jul 8, 2012
  7. 01exp4x4

    01exp4x4 Full Access Members

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    I am a little bit familiar with the ac period.

    I don't know all of the proceedures.

    But, if I have a bad compressor, its covered by Ford. If they want to throw parts at it, it's fine for me... Plus, they will put the factory specs of freon back in it when done.

    I watched the clutch quit working and labor to get going then stop and then start and stumble.

    So, I think maybe it's a part covered by Ford.

    I intend on learning AC no matter what. I want to understand.

    I'll let you know what happens. For now, the air is working and I am not going to take it in yet.

    What about letting out pressur from the low side. If it is not cold, is it just air? And same on the high side? If you let out pressure and its not cold, is it just air?
     
  8. stamp11127

    stamp11127 Super Moderator Staff Member

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    As a safety precaution only work from the low side. Depending on how far the valve is depressed you'll either get gas or a combination of gas and oil. With larger amounts coming out you should feel cooling. You shouldn't get "air" out of the system when venting the lines.
     

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