Krack Evaporator Icing

[Rob@goldcoast]

I am having problems of icing in a cooler, the cooler is approx 50'x100'x 30'. My temp goal is 34-38 degrees Farinheight, all product entered to room is also 34-38 degrees. I have three evaporators two for one compressor and one large Krack on its own compressor.All are R-22. I am using a dual controller I have had them set at 35 with 2 degree diff, They are set to alternate in air defrost . I know I am under refrigerated, but the system has worked for a long time. About three weeks ago our outside temps were higher than normal by 15 plus degrees My Krack sm25 started icing really bad I have been fighting ice ever since.The defrost clock had issues so i repaced it the controller went next so I replaced it I moved the probe in a more central location I haved played with the diff I checked the compressor found a small leak in the oil saftey switch so I replaced it and added 30 lbs of gas I noted it has a EPR Today we changed the evap pressure from 38 to 45 pounds. One week later the outside temp went back to normal but my problem still exists The people I work for , me and my refrig guy are all frusterated. Can any one give me some ideas?

[Dan]

A solenoid bypassing possibly? From your description, you are not frosting up more rapidly, but are getting incomplete defrosts. Are you using a solenoid valve to stop refrigeration during defrost?

[Rob@goldcoast]

Yes a solenoid valve is in line and is denergized by the time clock.

[Dan]

Maybe it is not closing completely. De-energize it and see if the tev is still feeding, or if compressor suction rises. If so, rebuild the valve.

[Abe]

If its icing up its an incomplete defrost
Do you have electric heaters or hot gas?

[Rob@goldcoast]

Only air defrost, I ordered elect heaters but they wont be here for a week. The frusterating thing is that this system worked before it is not a good system but I never had this much icing . This moring all the units are iced so bad I have to use water to defrost

[varader]

hi there!!
some times if you have a leake in your system and you dont have the prorerly amound of refrigirant (specialy in R22) the evaporator will filled up with ice.
Try to check for leaks and fill up the system properly.

(i'm sorry for my english ...)

[cool breeze]

Are the cooler doors closing and sealing properly or is the customer leaving the door open longer to bring in product which will bring in more moisture. Is the product different or wetter than normal. Look at distrabution header and tubes when cooler drops into defrost to see if you have an even pattern of defrost. Restricted air flow across evap. coil because of dirty coil, blower turning in wrong direction, product stacked to close to coil.

[bruceboldy]

I would agree with cool breeze it sounds as if the owner has changed a pattern, or product etc and not told you everything about the loading and unloading now.

espically if all of the units are icing which they were not before.

[Rob@goldcoast]

Same doors, sealed the same, with strip curtains, less volume or the same in the last two months. I feel the other two units are icing because they are trying to compensate for the Krack icing up. Today on this system we found a small heat exchanger that seemed to leak internally, so we pumped it down and bypassed it hopefully that will help

[Abe]

Same doors, sealed the same, with strip curtains, less volume or the same in the last two months. I feel the other two units are icing because they are trying to compensate for the Krack icing up. Today on this system we found a small heat exchanger that seemed to leak internally, so we pumped it down and bypassed it hopefully that will help

If its short of gas..............will only be a clump of ice around expansion valve.

I think it may be loading. offloading patterns which you not aware of, and doors left open for considerable time.

Also, certain periods, days.........you have very high moisture content in atmosphere.....During these periods evaporators tend to ice up pretty rapidly

[cool breeze]

Rob, how is that freezing evap. coil problem doing. Have you come up with any answers yet?