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  1. #14
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    You need to get Pro status, then the floodgates can open LOL

    Sent from my SM-G950U using Tapatalk

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  3. #15
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    icemeister, my thoughts also on thermal overload as compared to high amps.

  4. #16
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    There are no suction/liquid heat exchangers on these old bastards. I totally agree about it being more of a temp issue than an amp issue. Especially since this only happens in the summer. You can easily fill the sight glass during fall and winter on these. After going through some old pics Ive taken I just noticed that some of the condensers name plates say r-12 and some say 502 were originally in the system. Anyway here are the make and model numbers of the components in the systems.

    Condenser- MasterBilt M#RCLX-750 some say r502 was originally in the system and some say R12 was.

    Compressor- Copeland 9RS3-076A-TFC this is a somewhat newer version and it does look like there is one original compressor still in the bunch. Its model number is 9RS3-0765-TFC. From what I can tell the only difference is the older one wouldve had mineral oil in it instead of AB.

    Evap- Bohn m#FL-3302G
    Valve- Sporlan CSE body which I dont think they make anymore. If I recall I had to use a CBE on the one I replaced. They are 3 ton with a power head good for 502 & 404 at low temp.

    Im going out to give all the coils a good cleaning tomorrow. Hopefully it helps out but Im not real optimistic about it.

  5. #17
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    Quote Originally Posted by 2sac View Post
    I sold my first can of grey refrigerant yesterday. Happened to be 410a. Does anybody else see an issue with the new AHRI Guidelines? What could go wrong? We just had an issue where one of our distributors had sent us a pallet of orange 407c only it was orange 404a in 407c boxes...If they can't get colored cans in the right boxes....

    First we have gender neutral humans and now gender neutral refrigerant
    What is the logic in changing a refrigerant that has always been pink to grey???

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    "Call a technician for God's sake. Or we'll see you on the news or the Dark Side of the Moon."

  6. #18
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    Quote Originally Posted by JayMan7 View Post
    What is the logic in changing a refrigerant that has always been pink to grey???

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    https://www.achrnews.com/articles/13...er-the-rainbow
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

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    Liberalism-Ideas so good they mandate them

  7. #19
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    I bought a can of gray 404 a week ago. It’s just not right. One of things I love about this trade is all the pretty colors and now they’re taking that away.

  8. #20
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    Are there Head Master pressure controls on the condensing units?

    If so, could they be gunked up as other components are?

    Just a guess.....

  9. #21
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    There are headmasters. It doesn’t feel like any of them are sending hot gas to the receiver though. I took accurate temp readings on the headmaster last year when this was happening and they definitely were not bypassing the coil. Another thing I thought it might’ve been but have since shot down was broken receiver dip tubes. That was a long shot because of all of them doing it at the same time. But when I rebuilt that unit and it started working better, well obviously the dip tube was not broken.

  10. #22
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    The Copelametic 9RS3-0765-TFC operating with R502 is rated as XL or extra low temperature. This means that the compressor will tend to overload at saturated suction temperatures (SST) much higher than about -16F. The suction temps for R408A should be fairly close to those for R502, so you're looking at a maximum suction pressure of about 18 psig. Above that and you'll exceed the RLA. This then tells me that this system should have a CPR valve and not an MOP TXV because the MOP pressure limiting type valve doesn't throttle back the evaporator pressure until it gets to about 35 psig or so.

    here's the compressor performance data sheet for this compressor:

    Name:  9RS3-0765-TFC.png
Views: 75
Size:  110.9 KB

  11. #23
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    The operating pressures are about 250 psi on the high side and 14-15 on the low side when these are over amping and shutting off on thermal. You’re right about there not being crankcase pressure regulators on them. I don’t think the issue has to do with excessive suction pressure. Also, when I looked the compressor up on the CopelandMobile app it said it was rated for low temp and extra low temp on 502. It was also rated for medium temp on r12. So this compressor and the newer version should be good in a regular -10 freezer with a -20 coil. The fact that 2 of the 5 are doing good also proves that.

  12. #24
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    Quote Originally Posted by ImakesItCold View Post
    The operating pressures are about 250 psi on the high side and 14-15 on the low side when these are over amping and shutting off on thermal. You’re right about there not being crankcase pressure regulators on them. I don’t think the issue has to do with excessive suction pressure. Also, when I looked the compressor up on the CopelandMobile app it said it was rated for low temp and extra low temp on 502. It was also rated for medium temp on r12. So this compressor and the newer version should be good in a regular -10 freezer with a -20 coil. The fact that 2 of the 5 are doing good also proves that.
    The Copeland Mobile app shows only XL for 230v-60Hz operation. The 220v-50Hz model is rated for low temperature.

    At 14 psig you're running right at the RLA. That plus what I suspect is a high suction superheat due to undercharge or high evaporator (superheat or both) will surely put you into a overload trip.

    What is the box temperature when you're running 14/250?

  13. #25
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    Youre right. I was looking at the r-12 rating for low temp at 230v. But still, there are two working correctly. That alone tells me they all have the potential to work right. Also, the 2 that are working have equal to or greater length line sets than the others. The one I rebuilt has the longest line set at almost 200ft. Because of the excessive line sets, I originally thought it would never work right. I thought they would overheat no matter what. Because the compressors dont get enough cooling from the return gas I thought they might need a liquid injected cooler or something to keep these things from overheating. However, if that were the case, it would mean these things have never worked right. These things are 35 years old.

  14. #26
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    The reason Im leaning towards gunk in the systems is for two reasons. You can clearly see the tar like gunk in the sight glasses. Some were so bad you couldnt even see inside at all. After replacing the sight glasses and filter driers most have already started getting this tar looking crap in them again. The second reason is because of an issue one of them had and the solution that ended up fixing it. After replacing one of the filter driers, I start backing out the king valve on the receiver to let the juice out. The whole time Im watching the sightglass and nothing flows through it. Im immediately thinking this valve is screwed. Im getting ready to go up to the evap and check out the solenoid but I notice that the suction is starting to come up out of a vacuum. After it gets some positive pressure on it, I loosen up the flare nut on the sightglass to see if I can get some liquid to flow through it. Sure enough, as soon as I cracked it liquid started coming through. So I knew the king valve was good and my problem was either the solenoid or txv. Long story short, I crank the txv all the way in and out several times and finally hear a woosh of refrigerant flow and the compressor starts pumping away. At the very least, Ill be replacing that valve.

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