Fan motors: $340–$750
A built-in Sub-Zero has fans at both ends of its cooling: one inside, moving cold air off the evaporator, and one in the machine compartment, drawing air across the condenser. A failing fan often announces itself with a tick or a whine that comes and goes, then silence. When the condenser fan stops, the whole unit runs long and warm. When the inside fan stops, the section it serves warms while the compressor keeps running.
Control boards: $440–$900
The board decides when the compressor, the fans and the defrost run. It also gets blamed for faults that start elsewhere: a sensor reading wrong, a relay, or a loose connector can all look like a dead board. So we test those before we price a new one.
How we tell them apart
- Listen with the doors shut: is each fan turning, and does it sound right?
- Feel the airflow at the condenser and inside the warm section.
- Read the sensors against a thermometer.
- Check what the board sends out against what arrives at each part.
When no board is needed
A loosened or corroded connector, cleaned and reseated, costs far less than a board. A sensor that reads wrong is replaced in the $300–$600 range, and the fault that looked like the board goes with it.
Fan and board questions
My control panel is dark. Is the board dead?
Not necessarily. Check the circuit breaker first, then the plug if you can reach it. A dark panel on a unit that is still cooling points to the display or its connection; a dark panel on a warm unit points to power or the main board. We test the supply before anyone prices a board.
Can a noisy fan wait a few weeks?
For a short while. A fan that ticks or whines is usually wearing out, and when it stops, the section it serves starts warming within hours. Replacing it while it still turns costs the same as replacing it after it quits, without the spoiled food or the rushed visit.