Results 14 to 26 of 69
Thread: Walk In Freezer Woes
06-07-2012, 09:34 PM #14
Pump it down and clean the TXV screen.Never kick a lying dog.
06-08-2012, 01:12 AM #15
06-08-2012, 02:54 AM #16
Are you maintaining a solid column of liquid?
06-08-2012, 08:10 AM #17
Have you checked to see if a coil or pan heater is energized?
06-08-2012, 08:29 AM #18
cracker: it came with 4 orifices. two for r-22 and two for the various other reefers. the correct one was field installed
crymtide: its at 10 oclock and is horizontal. my bad there, the book shows 4 or 8 or 3 or 9 oclock. ill move it this morning after confirming its working. yes its insulated.
hvac and thermo: ill be checking the screen today. hard to believe i got trash in it since we bubbled n2 while brazing
phase: it was cool yesterday. sct was around 100 sst was -20 with a line temp of +5 deg. full column to the txv.
76: 0 amp draw from all heaters
06-08-2012, 09:26 AM #19
The OP has stated that he has the correct one in there, but I've found in a few cases, the nozzle size was a tad small for the application...especially for freezer pulldown.
Heatcraft's Refigeration Systems I&O manual has a good section of nozzle sizing (starting on p.7):
I would also recommend going up one size on the Q-Valve orifice, to a QC-4. The FJAL-B301 has a capacity of 9470 Btuh at -20ºF SST/90ºF Ambient but it's 13,100 at -10ºF SST/90ºF. The system seems to match up OK for the -20ºF condition, but it's clear the TXV will be undersized for pulldown.
06-08-2012, 09:30 AM #20
Thanks all Im off to the races Ill let you know what I find.
06-08-2012, 09:33 AM #21
My money is on the power head being bad. Doubt it is a MOP valve but that could also explain why adjusting doesn't give him movement.
06-08-2012, 09:57 AM #22
The existing head may well be bad, but if it were, I would expect the valve to slam shut.
Another possible problem, now that the TXV has been cranked every whichaway, is that the adjustment stem has been FUBAR'd...in which case a new valve would be needed.
06-08-2012, 10:16 AM #23
The head may not have totally leaked down, just the wrong charge pressure on it... want to see my box of old power heads?
Not to hijack but found this at a shiny brand new cooler install that went to the lowest bidder... that means we didn't get the bid but were asked to go back and fix it.... cheap aftermarket line set on both cooler and freezer, excess coiled up and left on top of the boxes (over 20' of access). 3/8 insulation instead of the factory 1" they require which was also sent by the factory with the proper length of line set... both boxes leaking water everywhere and temps were bad... SH in the freezer was 13, cooler wouldn't cool at all... You know those stories all too well.
See the pic? Installer took a torch to the body thinking it was internally iced. He couldn't understand why the valve wouldn't adjust. After we found the liquid side areoquip fitting at the condenser wasn't fully engaged/pierced this valve wouldn't adjust... don't know why.. HA
06-09-2012, 08:27 AM #24
Showed up to a -10 degree box yesterday. Stem at midpoint, still 25 deg sh. Pulled bulb and warmed it. Suction rose and suction line temp plummeted.
Screen had zero debris in it.
Reattached bulb and insulated. One turn away from being fully open and cannot get superheat down. Im stumped
Ive got a new txv but would like to know if you think I should stick a #4 in it before pulling and replacing?
Also..what damage can be done by adjusting the stem?
06-09-2012, 10:30 AM #25
06-09-2012, 11:23 AM #26
The fact that you got a huge surge of flow when the bulb was warmed up tends to lead me agree with what Dad was saying about the powerhead losing its charge.
Since you have to remove the powerhead to replace the orifice, I'd go ahead and replace the powerhead as well.
Then again, you may want to do the powerhead first, just to determine if it was indeed the problem all along.