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Thread: AC low side pressure okay, high side low

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    Default AC low side pressure okay, high side low

    What would make the compressor only run for a 5 seconds at a time ....cycling too quickly

    The low side pressure is 45 to 25 psi

    The high side pressure is 60-90psi

    All measurements taken while compressor is running at 40 deg F on defrost heat

    The high side pressure is too low....

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    Default

    I should add, I have had recent A/C work done on the car. The compressor is brand new made in Korea. I paid $140 for it from TechChoice Parts online (I know....you get what you pay for right?). The first one I got was making a ton of noise after I paid to have it installed. TechChoice Parts shipped me another one for free. I paid to have it installed and recharged again although I think TechChoice Parts should have paid for the labor, but its not their "policy". Okay so this new compressor does not make any noise when on, whew! But now it only runs for short durations like 5 seconds and all of the above symptoms....

    I changed the reciever dryer, oriface tube, and low side pressure switch also. When compressor is on, ice cold air blows out.

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    are you sure the system is full?
    Quote Originally Posted by zxtwou2 View Post
    Making bigger pipe as the exhaust flowd and cools makes eddy currents ehich is what mskes rasp.

    Helping raise some cash for our long-timer ZX2Fast. Parts here: click me

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    Default

    The low side says its full which baffles me.

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    what is the temperature outside when you're running it?
    Testing the limits of factory internals. Now at 18 PSI, daily driven.

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    its about 40-45deg F

    I tried the A/C and it works and blows cold, just dont want to freeze it up, thats why I'm using defrost, it runs the compressor also and it should be longer than 5 sec.

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    So there is a leak in the high side according to the shop that put the components in but they don't know where the leak is. I told them a blacklight is what they need.

    I think they are incompetent as this is like my fourth time going in for the same damn problem.

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    at 45F, the compressor will only run for a few seconds at a time. When it is that cold, the static pressure of R134A is 40 PSI, which is barely high enough to close the low pressure switch. When the compressor kicks on, it pumps the refrigerant from the low side to the high side and will pull the low site lower than 25 PSI, which will kick off the compressor. Wait until it is about 65-70 out to test an AC system, as at that temperature, it will run for a few minutes before it kicks off.

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    Also a leak in the high side will be plainly evident by the leaking oil and dye and dirt that will inevitably stick to the oil. At normal operating pressures (Low 25-40, High 175-400 PSI) even a pinhole leak will be plain as day.

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