Hi, first time posting here, so you'll have to bear with me. I have a Norlake freezer model # ZF122SMS/0-2 Serial # 99120491 that I cannot get below 0 degrees at best mostly hangs around 3-6 degrees. Now just for some brief history....When I first started on this thing it would hold -5 easily, the box temp. began to creep up slowly, I cleaned the condenser thoroughly and right back down to -5 or better. I also repaired a short causing the fans to stay on all during defrost. Never touched the refrigerant circuit. Well, about a month later the temp. was back up again, there was no low side port so I frontseated the suction service valve and put a swivel tee on to accomodate the LPS. This is 404-A with Sporlan EFS 1/4 ZP 1/4" * 1/2" ODF. Copeland condensing unit 1/2 HP compressor, no receiver, HeatCraft evap. Model # CCL16AF Serial # D99HOO362. I found that the evap. was being starved to death, frost pattern on the coil was only the first row if that, and running around 50 degrees superheat. I had no reason to believe there was a leak but I recovered the 23 oz charge anyway and took the valve apart. I found some, what I would call "residue", black in color around the port and on the needle and carrier. I cleaned the internal parts of the valve and reassembled, installed a new drier. Leak check with Nitrogen, Evacuate, charge. Once the temp. was at about 6 degrees, it would go no lower because I couldn't get the saturated suction temp. needed to get below that, adjusting the valve would only cause flooding (0 degrees superheat at compressor) or would starve the evap. again, absolutely no modulation from TEV at either condition. Head running around 305 and Back will not drop below about 25 psi. It will if I turn the setting on the TEV in all the way in which case I completely starve the evap. So really my problem is that I cannot achieve the suction pressure I need to be at with a full evap. I've spoken to a Sporlan rep. and He suggested that the compressor may be at fault, not able to achieve the compression ratio I need, I valved off the suction line and the compressor will pull about a 10" vacuum and hold it. I need help! Things just aren't adding up, pressurewise on my gauges it looks like I have a full evap. and when I open the TEV by adjustment the head skyrockets and so does the back naturally but superhaet is either flooding or starved. Subcool is around 2 degrees at best. I've been through so much crap with this thing I'm sure I'm leaving out important stuff but if anyone has any Ideas at all I'm all ears. Thanks in advance!
I'm sure you realize the TXV is an MOP type and they take a long time to pull down. That said, go to http://www.copeland-corp.com and register. When you get into the website go to online product information. Then search for your compressor, print out the performance table/curve and take it to the jobsite to check amps versus pressures. I've had problems with Norlake freezers in the past as well. I don't think they dial in much of safety factor when they size their equipment.
Need a little more info. How hot is the area this box is in?
As far as the compressor it should be able to pull at least a 20 inch vac and hold with no problem. If not change it. I also like to have a receiver an all TEV systems.
How long does it take the unit to pull to 3-6 degrees?
Are all the fans running? Hell I had one that the defrost heater was still entergized, bad defrost timer.
I think that I would go ahead and change that TEV also.
It's about 75 to 80 degrees in the area of this unit.....it is in a dairy queen store, directly behind the counter. It takes approximately 2 hours to get to 6 degrees. The heaters are definitely not on, I've wracked my brain looking for stuff like that I may be missing but the prob is most definitely in the refer cycle/circuit. Fans are running just like they have from day one. The TEV and the evap coil are brand spankin new. This unit does sit in such a way as to recirculate condenser air but all the units in this place do that and it's always been that way. I agree, at least with the design of this unit Norlake left NO margin for error, if even small amount of capacity is lost the temp is up. I am already registered with Copeland but could not find those charts when looking in the past, I will look again. I am aware of the valve being MOP type but this machine will run from now until kingdom come and still not get below zero if it ever even gets there. I don't know, since replacing the TEV I never touched the stem adjustment, possibly I can get it by playing with that. I'm running out of variables though. Thank you for your replys..... :-)
Many of them freezrs left no margin of error, when it gets hot you can't get the temp down, forget about storing ice cream in some of them.
You are saying it used to be -5 and now only gets to 6?
Hmmmm if the ambient is the diff you just don't have enough HP. Bally used to make walk-in's that were very marginal, on a hot day them liquid lines smoked. Hard to say from here but maybe get load on the box and the equipment before you go any further.
If it pulls to 10" only, sounds like a suction valve in compressor problem. I think chpc gave you good info.
Whats the model number of that copeland condensing unit?
I believe that heatcraft has changed that evaporator to a TLT model now, I'm not sure.
Another thing on that TEV you might want to try a sporlan EBS 1/8 ZP valve that should lower your evap temp if you are trying to store ice cream. With that valve you maybe able to get a -20 evap instead of a -10. These are just a few more things to check into.
Your local supply house should be able to help with this info.
I don't have the condensing unit model number.....I will probably be going back there soon, I will get it then. I did find the performance chart on copeland's site for this compressor and at the Condensing temp. and evap. temp I used it was drawing more than rated current at that time. I don't know but this one's got me stumped. My background is mainly in A/C working for Trane. Switched jobs and I'm getting more into lower temp refrigeration stuff and not having much luck either! Thanks for all your help
You have a performance problem here.
I'm with 1234. First establish whether or not the unit itself is to blame.
I would also agree with DiceMan, but that would establish a precedant and I dont wish to establish such a thing right now.... He's already got a puffed head ... if he had people begin to agree with him ... there'd simply be NO living with him AT ALL!!!
I assume you used the same capacity filter drier when you opened up the system. Otherwise that new drier would seriously affect your overall performance.
(you know this ... it's only meant as a reality check).
Is it possible there is foreign matter inside the system? You mentioned black substance found.
POE has some funny characteristics once it gets too hot.
First rule out the compressor as being part of the culprit.
Next I would sugest using a thermometer on both liquid and suction lines while you are charging this system.
Let's do this one more time. This time write down all events and temps as the system is being recharged for the third time.
There will most assuredly be one single point where you will notice the optimum performance.
Less freon and not as good performance. More freon and a noticeable decrease in performance will also be noted.
I have not played with 404 as to be aware of just how user friendly the stuff really is.
If it were me, I would use some good ol' 502 and add some, then subtract some and see what amount suited this system the best.
I would use a small Dial-A-Charge.
I dont know how well 404 holds itself together, in this small amount of charge, against fractionization.
But for trouble shooting purposes alone, I would sure love to diddle with this system using a real refrigerant and NOT this blended concoction dupont peddles us these days.
Wanna-be freon is NOT freon at all. It's only gas.
And if you will settle for only gas, just ask DiceMan and he'll introduce you to his freind Jack. (his maskot)
Jack's ALWAYS got "gas"!!! Plenty to spare ... as a matter of fact!!!
One basic but important beginning thing you should look at is simply you door gaskets, and look at the defrost timer. If you got to much frost between defrosts you might give it more times. Also the lenght of time, to insure enough heat to melt all the frost or ice. I don't know if you have a termination or not, but put it defrost and watch to see if all is clear on that coil. The best and coldest coil is a clear one with no hot air continuisly coming in from leaky gaskets or holes in the box frosting the coil.
norlake my Favorite! (besides Corneliius...)
I feel for you! It seems a damned if you do or don't situation sometimes huh?! How much time and material can a guy put in to this kind of eqpt and not EAT alot of it!
I also looked at a norlake that has mp 39 in it, 2+ hundred a jug. not stock presently....
I need to go talk to the customer tommorow and tell her that this may get more exspensive than she wants to pay for this junk! probobly 30 years old..Cooler...It was all iced, thought it just might be an evep motor. no such luck. cfm is probobly as always was, seems low to me, but I checked pretty thourough, and it doesn't appear to have been altered recently. temp in the room o.k., gaskets o.k., charge "seemed ok by my pressures, No glass... but it ices pretty quick right outa tev? damn amprobe was broke! I'll go back with another. any more ideas to go back with?