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Could anyone provide SIS info on my Air Cond charge/system?

Discussion in 'Excavators' started by fastline, Jun 11, 2022.

  1. fastline

    fastline Senior Member

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    This is the 322C kiddy, HEK serial. Got machine with a leaking AC. I work on HVAC so not really a big deal. Got that stuff patched up, pulled a bunch of moisture out of the system, and weighed in the charge. Life should be perfect now. However, vent temps just don't impress me. I would accept it as "is what it is" other than by the data, it really looks like the TXV is underfeeding. Lower than ideal suction pressure, coupled with a bit higher suction line temp. At full throttle I have around 20* of superheat and subcool. Due to the subcool, I am not sure I would try pushing the charge up right now. The superheat seems to hunt around quite a bit, but I realize this is a mobile application. Just not sure if there are target values from Cat. It was mostly hovering around 10-12, and that really should be about right.

    This TXV is odd in that it does not have a sensing bulb. I has the hat, but no extension line and external bulb. I'd really like to know more about the TXV and any related charge information.

    my suction temps was around 42F. I am sure if I let it run for hours, it would get lower but that coupled with the low suction pressure leans towards underfeeding. If I could easily adjust the TXV, I'd be a happy man! Or I can find a way to lie to it so it will get the job done.
     
    Last edited: Jun 11, 2022
  2. Cmark

    Cmark Senior Member

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    This is about all there is. Have you had the HVAC box apart to clean the evap coil? They can get pretty bad.

    upload_2022-6-12_15-43-14.png

    upload_2022-6-12_15-44-32.png
     
    CM1995 likes this.
  3. fastline

    fastline Senior Member

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    I was afraid of that! thank you for looking up the data! If there is a PN for the receiver/filter/dryer, and the TXV, that would be super helpful!

    As part of my service work last yr, I did take the front off the evaporator housing and cleaned it. I would certainly be looking at a plugged evap other than airflow in the system seems to be quite substantial. It's windy! Usually a plugged evap would have flow issues.

    Basically I am seeing superheat that is higher than it should be, which points to underfeeding for some reason. Usually we would want to add charge but subcooling is already pretty high, but I might expect that having a receiver on it. Usually with a plugged Acoil, I see very low suction temps or signs of frosting as there is not much air exchange. The TXV would clamp down and try to reduce feeding in that case, which would show the low suction pressure.

    Right now at high idle I am about 19psi and suction temp of 42. No doubt it is cooling but that 19 is a guarantee something is not right.

    One thing I am unable to confirm right now is any restriction in the receiver. I really don't know what is inside it. If it has dryer media, I might have screwed myself in not replacing it as the media can become restrictive. That would certainly cause all of this. I can 100% tell the TXV is functioning and attempting to regulate flow. I don't know if there is a strainer in the liquid line that could have crap in it or what.
     
  4. Cmark

    Cmark Senior Member

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    Rec/dryer is 1761902. It's fairly common. Should be available aftermarket.

    There are two options for the block valve. Unfortunately there is no good way of telling which one you have. A full serial number might help. The early one is 1776723 and is no longer available (from Cat). It updates to 2289044 but you also need to replace the evap coil to use it.

    upload_2022-6-13_6-5-57.png

    upload_2022-6-13_5-55-53.png
     
  5. Cmark

    Cmark Senior Member

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    There is also this.
     

    Attached Files:

  6. fastline

    fastline Senior Member

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    Cmark, thanks a TON for the info! That got me what I needed. I confirmed the evaporator mod was already done, so I know I was not the only one that was less than impressed with the system.

    However, I have concluded I don't believe there is a thing wrong with the system. The core of the issue is all the cab air leaks! The door needs replaced and I plugged all the holes, grabbed some cold ones and sat in there for 30min. System pulled down in about 20min to where it would cycle and was getting 45* air from the vents. Just going to have to figure out the air seal issue.