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08-13-2007, 10:58 PM #1
Norlake Freezer Unit Mystery - any ideas?
Customer calls: "freezer is warm. Just needs freon. A customer checked and found out. Come and charge it up."
Get there. "it was not running - my customer he look at it - he adjust pressure - now running - no cold enough - he say needs freon"
Great pal - mind if I check for myself?
The unit and walkin are five years old. Customer says there have been no problems except a stat was replaced a few years ago. I believe it - no wrench marks on access or valve caps.
I find: R-404 system. Copey iron body (KAJB 010E CAV100) Sight glass is clear - shows dry. 111 degree condensing temp. Liquid line is 102 degrees from the receiver outlet, both side of the drier, and to the TXV. Evaporating temp is about zero. Suction line temp is about 70 degrees.
I conclude that it does not need refrigerant. I screw the TXV stem all the way out - no change in suction pressure or line temperature - TXV must be bad.
I call NorLake and ask them which valve they used. They tell me some 1/2 ton Sporlan # (EFSE-1/2-ZP) that I don't have but I locate one on the phone and go get it.
Working in a 105 degree attic, on top of the box - 11" clearance over the NorLake evap box - 12" clearance alongside - I R&R the valve along with a new Sporlan 163-S drier. Valve bound in wet strips of cloth, Stay-Brite solder joints. Propane torch. Valve barely warm to the touch the whole time.
Open the condensing unit valves, the unit starts, the evaporating temp is 19 degrees the suction line temp is 8 degrees. Frost happens right to the suction service valve. Cool - I'll wait for it to stabilize a bit and drink Gatoraide. Line temp hangs at 8 degrees for a few minutes and starts to climb. Stops at 60 degrees and remains.
Hmmmm . . . recheck: subcooling is 7 degrees. evaporating temp is 20 degrees. Suction line temp is 60. Damn - now what?
Box temp is 27 degrees. I screw the TXV stem down (open) a few turns - no change.
This evap coil is six rows deep - face about 12" by 30" Has heavy frost on first row fading to slight frost on the third pass. Nothing after that. Four distributors - all with even frost.
Can the valve really be too small with the coil temp so high? You would sure think it would be wide open with a 60 degree suction line. I am just guesstimating but I would think a 1 HP compressor at a -10 suction would be pumping about 3000-4000 BTU's tops. A 1/2 ton Sporlan with a 200+ lb. PD would flow maybe 7000 BTU's?
It has been my lifelong experience that TXV's rarely fail.
This is looking like a restriction of some kind to me at this point - and apparently at the TXV. OK maybe once - but twice? First a bad TXV and then another one right out of the box? Come on now.
Have I just just been brain-fried back into a one month apprentice? I poked around for a few minutes but at 9:30P I called it a night. Told them to let it "stabilize" and I would check it in the morning. <g>
So? What do you all suggest?PHM