Sub-Zero Code d0 0r: Door ajar alarm — door left open over 5 minutes

Code d0 0r means: Door Ajar Alarm is off; door is left open more than 5 minutes; audible alarm chimes. Alarm stops when door is closed. A 5 minute UIM…. It falls under alert / indicator code — Alert codes are the unit telling you about a condition, not necessarily a component failure — a door left open, a control panel key stuck down, or a brief power interruption.

Often yes — if it was triggered by a door left open or a brief power event, closing the door or power-cycling the unit will typically clear it.

Yes — alert codes describe a condition rather than a failure, so there’s no cooling risk unless it keeps recurring for an unclear reason.

That usually points to a door switch that isn’t detecting the door as fully closed, which is worth having checked.

It can, if it recurs with no obvious trigger — that pattern usually points to a switch or control panel issue rather than the original alert condition.

Not usually — if it cleared on its own after the triggering event and hasn’t returned, it’s not something to worry about.