Storing and draining
Water circulation pump
What keeps water moving over the plate, and the part scale reaches before anything else in the machine.
- What it does
- It is the pump that takes water from the reservoir at the bottom of the machine and drives it up into the spray area, over and over, for the whole of a freeze cycle. Nothing else moves water once the inlet valve has closed, so a cube only forms while this pump is running.
- Where it sits
- Low in the machine compartment of an undercounter ice maker, with a short vinyl hose on its outlet. That hose is the one Sub-Zero has disconnected and drained when a machine is being shut down over a winter.
- How it is tested
- By ear and by result. A pump on its way out whines, rattles or goes quiet mid-cycle, and the batch that follows is thin or missing from some cups. On the bench it is checked for a seized rotor and for scale in the impeller housing, and its flow is watched with the shutters lifted rather than assumed from the noise.
- What the work costs
- Ice maker, water valve or supply line: $300–$820, after the flat $89 diagnosis.
Pattern
What we usually find
- Scale through the impeller and its hose, because the same water passes this pump again and again inside one freeze cycle and leaves a little behind each time.
- A reservoir run low, so the pump draws air, the spray breaks up, and cups on one side of the bank fill while the others do not.
- Bearings gone dry, which is the whine an owner hears months before the cube size changes.
- A pump that is fine and a supply that is not: a short fill leaves too little water for it to move.
Most often first. Order comes from what the visits keep turning up, not from a count.
A built-in column has no part like this. It fills a tray once and leaves it alone, so there is nothing to circulate and nothing to wear out. The clear-ice machine trades that simplicity for a moving part that runs through most of every cycle.
Which is the honest reason these machines want cleaning on a schedule. The pump is the part the water works hardest.
Repair or replace
What usually happens to it
Cleaned first, replaced second, and the order matters because scale is what usually slows it. The cleaning and sanitising cycle carries cleaner through the pump along with everything else the water touches. A pump still noisy or still short on flow afterwards is worn, and it goes back as a unit with its hose and seals.
Two follow-ups
Is the circulation pump the same thing as the drain pump?
No, and they fail differently. This one moves water inside the machine so ice can form; the drain pump lifts waste water out to a drain sitting higher than the cabinet. One announces itself as bad ice, the other as a wet floor under the plinth.
The machine has started whining. Should I switch it off?
Switch it off at the control panel if the noise is new and loud, then call. Running a dry or seizing pump does the ice no good and the bearings no good either. Denver Sub-Zero Repair Experts would rather hear the noise on a working machine than reconstruct it afterwards.