Reach in Ice Cream Freezer

[Toddbrewster]

I have a customer with a reach in ice cream freezer, the type with a glass cover with the tubs of ice cream where you can go look and see what kind you want. Its an old kelvinator, semi hermitic compressor, r-22. Originally I found the unit tripping on high pressure due to a completely plugged condenser, this condenser has no fins just copper tubing looped back and forth about an inch apart with a fan pulling air through the coil and pushing it over the compressor. I cleaned the condenser, the unit would run but the pressures were off, and still tripped the high pressure switch intermittently. By the look of the pressures I thought it had a plugged liquid dryer or a blocked cap tube. I pulled the charge, replaced the dryer, which seemed clean, blew nitrogen through both ways and no blockage and nothing came out. Purged nitrogen through the high and low sides and all seemed clear. Evacuated to 340 microns, pumped the charge back in, and now the cooler is working fine, about 200 discharge, but only 0-2# suction pressure with about an 80 degree suction line. The box started at about 75 and with in a half hour was down to about 18 and still running. There is no evap fan so I understand the suction will be low but the pressures and superheat still look off to me, the cooler is working fine now, but I am a little confused on what superheat and subcooling to look for, and it seems as though this compressor would need cooler suction temps to keep it cool, the fan is blowing air over it, but something just doesnt make sense.

[K_Neil]

R 22 seems strange for ice cream freezer

[jhd1234]

Where is the suction line piped to the compressor? If it goes to the head, it's air cooled. If if goes to the motor housing, it's refrigerant cooled. If the compressor is a Copeland, the second letter in the model # tells you. A = air cooled R = refrigerant cooled.

[Toddbrewster]

yep I forgot the suction goes to the head and it is a copeland but dont have the model number handy. I thought r-22 was an odd refrigerant to use in this application, but I talked to the factory and thats the original charge, and I can even still order lid gaskets for this unit!

[jhd1234]

Well, the total suction superheat is around 116F to 120F [evaporating temerature plus 80F suction line] which seems excessive. Additionally, the condensing temperature is about 103F. I agree that a static evaporator will have a much higher TD than a forced coil. A dipping cabinet is usually about 2F to 5F, just soft enough to dip the ice cream but not so soft as to be runny. It looks to me like the evaporator TD is too high and the condensing temp is too low. You had mentioned that you put the charge back in. Did you weigh it in? On a job like this, I used to weigh in a fresh charge [virgin refrigerant] to the nameplate specs. My initial suspicion is the box might be slightly undercharged. Also, is the drier oversized? I used to like to point the drier at a 45 degree angle towards the cap tube.

[codgy]

Are you sure the box was always r-22. Only seen semis run 502 or on boxes from the 50's R-12. There were some r-22 hermetic units for a few years when r-12 first went away. Verify refer and if it was r-502 convert to 404a and your golden.

[LKJoel]

I used to like to point the drier at a 45 degree angle towards the cap tube.

Why the 45 degree angle?

[jhd1234]

Why the 45 degree angle?

I had seen it done by manufacturers. I believe it's to ensure that liquid refrigerant is entering the capillary tube. I started to copy the idea.

[Toddbrewster]

No kinks in the suction line, the cap tube is not soldered to the suction line but wrapped around it and both are insulated. I didn't check the compressor to see if it was original or a low temp compressor, but the unit has been running fine now for a month, no complaints from the customer. Still havent been back to clean the ice machine they want to do it themselves, I just hope they do clean it I cant stand seeing crusty ice machines!

[codgy]

Just reread your post, did not know they made any semis w/r-22. Great info. Agree seems low on charge. Check for kinked suction line behind slideout.

[Toddbrewster]

Yep r-22 is the factory refrigerant for this cooler, nameplate calls for r-22, if i remember correctly it said 19 oz, which seems like a small charge for this system, see a lot of window shakers take more than 19oz for a small 5,000btuh unit! I weighed the charge out, about 2lbs, and pumped the charge back in with my recovery unit, added about 4 oz to make up for the loss in my hoses/recovery unit, re-used the old refrigerant, was trying to keep my cost as low as possible for the customer as with the original readings I thought the cap tube was blocked, this was an "experimental" quote as I told the customer this may not solve the problem and if I was not able to clear the blockage in the cap tube, there was not much I could do, no way to get to it to replace it without ruining the cooler, usually though I would use virgin refrigerant. The drier was not over sized, .8 cu in of desicant, (ek-082) which was what the original was. I agree the superheat is crazy high, but to my surprise I stopped back the next day and it was running a 10f box, asked the owner if that is the temp they want and that is the temp they usually maintain, I mentioned I thought it was a little high but maybe their thermometer is off by a bit, but they were happy with it, only complaint they have is they have to defrost it quite often, which is not a huge surprise to me when its as humid as it is now and they are opening the lid all of the time to dip ice cream, they asked if I can get replacement lid gaskets and I talked to the manufacturer and to everyones surprise the lid gaskets are one of the few things I can still get for this unit. The manufacturer told me this unit was from 1993 and they were surprised it was still in use.

As to the suction line behind the slide out, it is not kinked, they left a nice coil to pull out the condensing unit, but the unit only slides out about 10" makes it hard to get my hand in to get gauges on the king valve, so the suction line doesnt move much at all, but good call i appreciate all of the help! I enjoyed what I have learned on this unit although the high superheat still has me confused, I checked the temp and pressure several times, but the unit is working just fine now and the customer is quite happy they can sell ice cream not soup!

[oldfart]

I'd be suprised if that was the orginal dryer. Manufacturs don't usually install a dryer like that in the orginal system. Generally they use a copper bullet type dryer, If so, that would mean that the system was a little undercharged as one of the other readers mentioned. Perhaps your not the only one to work on the freezer. Just my two cents worth.
Oldfart

[Toddbrewster]

I didnt ask the manufacturer what dryer was installed originally, looks like it was original, has a bracket to hold it and all, but like you said I have no clue if I was the only one to service this unit. I did add about 4 oz of r-22 to it and it is holding temp, so I have not added any more r-22, but would like to re check the pressure/temps when I return to clean the ice machine, problem is the bakery/resturaunt has been closed a lot lately.

[timebuilder]

I didnt ask the manufacturer what dryer was installed originally, looks like it was original, has a bracket to hold it and all, but like you said I have no clue if I was the only one to service this unit. I did add about 4 oz of r-22 to it and it is holding temp, so I have not added any more r-22, but would like to re check the pressure/temps when I return to clean the ice machine, problem is the bakery/resturaunt has been closed a lot lately.

I'd be asking for cash for each visit.....

[heresjohnnyb]

If you see there was work done on the refrig. side. i Would find the factory specs for the cap and the drier and replace both. Also i never re-use refrig. hopefully you put it back in the system through a drier.Check to see if it is a low temp comp if it is not the original.Good luck

[MicahWes]

You say earlier that the nameplate charge is 19oz, but you have put 40oz in it now (32oz + 4oz + 4oz)???

[hydra]

The two critical points to check for suction line kinks on these slide out skids are the last bend before it enters the compressor and right where it enters the refrigeration cabinet. Old copper becomes brittle with age and will kink easily in those spots. Also, if your cap tube is soldered to the suction line, it will throw off your superheat temp.

[hydra]

Those fractional hermetics are real workhorses. I'm amazed at the abuse and neglect they suffer yet still keep pumping!this is just one example I run into!