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SubZero UC-15I - Poor Cube Quality


Premium Member
Jun 6, 2022
Model Number
1-5 years
I have a 3yr old SubZero UC-15I undercounter icemaker. Over the past three years the unit has slowly degraded in cube quality until about a month ago when it simply wouldn't fill the bin and the cubes that were coming out were basically thin little shells. I called in an authorized SubZero repair company and they saw the issue and could not figure it out on site so they took the unit back to their shop. After a week or so they called and said it was working fine, the dimple in the cube was about 1/2 inch or so (this is still not good quality ice though it is much "Better" than before). They said they worked with SubZero Tech Service and they said it may be the waterline and not having enough pressure. I find this odd since the unit has been degrading over a three year period so I checked the line and it has very high pressure so that isn't the issue.

They reinstalled the unit on Friday and I ran it over the weekend. The cubes are better but not at all what they should be. I have added the 5 minute freeze cycle time and they still come out of my unit with a dimple between 3/4 and 1/2 inches deep. Leaving a very thin cube. My family has the exact same machine and I checked their ice and there is less than a 1/4 inch dimple making a VERY solid cube. My cubes are simply subpar. I also have a new Scottsman in my home (in another room) and it makes perfect ice just like the SubZero at my family's home.

I have kept fully up with the maintenance on the units:

- Replaced filter every 6-8 months. Current filter is 3 weeks old.
- Cleaned the radiator fins every 6 months or so
- Cleaned and Sanitized with official SubZero chemicals every 6-8 months

The only other thing I could think of is that I have it installed in a bit of a shallow cabinet so there is very little space between the back wall and the unit...maybe 1/2 inch. So I also pulled some of my cabinet trim away to ensure the unit is not overheating and the problem still exists.

The odd thing is that at times it will produce so much low quality ice that it NEVER shuts off and will fill the bin to the very very top where when the door opens it all falls on the floor (the Repair Service also saw this when they took it to their shop). So it produces enough ice at times, never senses enough ice to shut off and all the cubes are low quality. This morning I even had cubes come out where there was a hole completely through them so the dimple was as deep as the cube itself.

I know there is something wrong with this machine but SubZero refuses to give any clue except low water pressure yet the reservoir is completely full and the pressure is just like it should be. I am lost here, all I can think of is that the cube tray is not cold enough to freeze the ice in full but with a sealed system there is no way to check for low refrigerant except to tap into it which could cause problems downline.

Anyone have any sugestions? I am about to pull this damn thing out and go full office space on it.

Your warranty is 2-5-12. If you have added the freeze time to max(5) and still can't get the 1/4" dimple(that's right in the manual) I would call SZ directly. They are usually pretty good with assistance($)
I will try calling again to see what advice they have and I hope they don't say water pressure again.
Don't call the service co. call 800-222-7820 and tell them your issue. Have all records of service on hand. You're only a year out of full warranty but still within full sealed system warranty.
Will do. Thank you for the number! Do you think I am out of line believing that it is the sealed system and low on refrigerant?
So I just called them. They assigned a case number and are assigning an "Advocate" to the case. I was told I will hear from the advocate in two hours on next steps.
Weird. Maybe handling differently. I'm now working on a 16 year old double wall oven that needs a bake element, r/s conv element and a relay board and they're sending customer the parts.
Quick update to this in case anyone else has this problem. I worked with SubZero directly and they assigned an advocate. They asked me to film videos of the machine install, the various parts working and the resulting problem with ice quality. I sent it all in and they just informed me they are scheduling a repair service to come out and change the "Board, updated alternate fan motor and an airflow kit". Let's see if these items make a difference. I just hope they can get the parts in and come out in the near future.
Didn't work directly with a tech at SZ....my SZ Customer Care Advocate worked directly with them.

I was just told the repair service will come get the unit from my home and replace the parts at their shop. Here is to hoping it solves the issue!!
Update. The following parts were replaced / installed:

- Upgraded Compressor Fan
- Control Board Replaced
- Air Flow Kit

After working with the machine all weekend the quality of the ice is marginally better but still not even close to where it needs to be. The divot in the cube now averages between 0.5 and 0.75 inches when I extend it to add the 5 minutes of extra cycle time. I still have cubes that come out as shells in almost every single batch. This is an improvement from all cubes having a 0.75 inch divot or more before the changes. The manual says the divot should be 0.25" so I am still way off.

I also tried directing the airflow differently from the machine to ensure the hot air coming out from the compressor is not being sucked right into the radiator coils. That also did nothing. I opened up my cabinet to allow for 2.5 inches of space on the left side of the machine so there should be no issues with heat at all. When compared to my Scottsman machine which is shoe horned into a cabinet and works beautifully the SubZero is basically in an open space with 68 degree ambient temps and it produces a heck of a lot of heat and poor ice.

I documented photos of all the different cycle lengths and how the cubes looked and sent them to my Sub Zero Customer Advocate. He has been patient with this problem and I hope he can find a solution with their technical team.

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