Professional Member*
Ive got an old hussmetic condenser with an old copeland 3 hp semi that locked up. After talking with a refrigeration parts house i discovered that this was an old r-12 low temp system. The customer has been using this as a med temp cooler supposedly for 5yrs no problems(that's how long they have owned bldg. it is not a pumpdown system. It had 409a written in the box so i'm assuming that's the drop in that another company put in there..the powerhead/txv was too rusted to make out numbers. Russel evap on indoor, 3/8" liquid line, 1 1/8" suction. The old lal copressor crossed over to a Lacb-032e-cab-800. They said it was an r-12 comp that could be used for medium temp just needed to change out the poe oil so that's what i did. I also had them build me a med temp r-12 power head. I chanfed comp and txv, drier. Recharged system and turned on.. Few hrs later when box temp was around 45 i looked at superheat subcooling but forgot to check amps. Superheat at evap around 8-10. Superheat at condenser was around 32. Subcooling was a little high like 17. But was cooling fine...5 days layer comp locked up and i couldnt get it to break free(yes i put new starting components on the compressor befor i started it up. So i changed compressor again, new starting components, and converted to a pumpdown system. I charged system differently this time. I found that at the right freon charge im over amping compressor by 5 amps. Fla is 15.5. So i took freon out. Dropped amps to 15.2-15.6 range. My sight glass is bubbling. My super heat at evap is now at 15-20 with superheat at condenser being 40. Still pulling down temp ok. I know this isn't right but i don't want to loose another compressor. I think my problem is my txv. Since im using a low temp compressor with low temp freon i should go back with a low temp valve/powerhead so i can get freon charge right. Are there any other possibilities? Also had the brus checked. 23000 btu valve,compressor at med temp, and evap. So that's right. Maybe going back with a low temp valve and adding a cpr valve is the longterm solution as apposed to replacing condenser with a med temp one which customer won't do now that they have a compressor.
Professional Member*
Craze,
First, you should use paragraphs when writing a post this long. It's difficult to read and comprehend the way it's written.
The LAL does not cross to a LAH. It is still a current model (with slight changes in the motor)
LAL1-0310-CAB
774 CFH
MT R12
LT R502
(It is not a LT R12, that would be the LAM)
LACB-032E-CAB
816 cfh
MH R134a
XL R404A or R502
Your TXV theory is incorrect. You might want to get a seasoned refrigeration mechanic to help you out.
Professional Member
I have learned never to trust a supply house. Sounds like you shouldn't be trusting yours. Emerson makes it easy to sign up at their web site and get the correct info on any compressor they have ever made.
Professional Member*
I'll try emerson sight tonight. And im a little short on "seasoned refer techs" in my phone book. So that's why i'm asking here. Insight and direction. I know only basics and am doing the best i can with what i've got.
And the copeland i can't remember original model number and the note in phone got erased. But they pulled up the emerson website and put that model number in and it crossed to the one i installed.
Professional Member*
OK,
Let's assume the original compressor was a:
LAC1-0310-CAB or LACA-031A-CAB
MT12
LT502
It does cross to a LACB-032E-CAB
The CAB designates 230V only, not 208/230. Could be your amperage problem.
Fill out your profile and let us know something about you.
Professional Member*
I saw that new compressor was a 230v, i had 230 to the outdoor breaker but 208 on outlet side, i replaced so i now have 224-230v at compressor contactor, contactor is new and on outlet side of contactor I've got same voltage. Will fill in profile once i get home..using tapitalk from my mobile to view website currently...
Professional Member*
And that first m# u posted really looks like the original one. So i do have the cross for that one..and if assuming that it was running ok for 5 yrs prior to the failure. The only really other component i changed was the txv because i couldn't make out original one....i want to saw qfv or something like that was etched into the sporlan body
Professional Member*
May have been QFE
Professional Member*
Miami has a good Copeland supply house, just find the seasoned help who learned by looking in catalogs, not the web.Originally Posted by Russ57
Or come see me.
Professional Member*
I'll get more numbers of everything tonight but i gotta stop this thing from over amping at full charge
Professional Member
Try front seating compressor suction valve untill the amperage behaves at full charge. Do not leave unattended. If it does start to look ok after a few cycles an OPR might do it. Low temp compressors on med temp applications have needed them before.
Professional Member*
Sweet...i will try that here in about an hr. will let ya know how it turns out
Professional Member*
Cpr sealed the deal...low temp powerhead i didn't even try. I closed off on the suction and added a little more gas. Superheat at the compressor is still about 32 but it is ran with the liquid line acting as a subcooler for the liquid line. I tried to tell customer that a cpr valve needed to be installed but he wouldn't go for it. I noted it on my ticket and left the suction cranked in..been running for almost 3 weeks w/o an issue..just checked in on it the other day..still eerie of it but it's running and cooling
Professional Member
Most of the R12 drop in replacements raise the head pressure significantly. It is a good idea to change the whole condenser when dealing with a dead compressor on one of these old beasts. You can then size the condenser properly and it usually ends up costing the customer about the same because you save some labor with a complete swap out. Change the TXV and go to 404a or something that isn't ancient technology.
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