Sometimes the display remains dark, and no error code is there to guide you. If your sauna is unresponsive, it's time to open the "brain" of the unit—the main control box (usually located on the roof or under the bench).

1 The "Sniff Test" (The Smell of Failure)

Electronic components like Relays and Transformers release a distinct, acrid "metallic" smell when they overheat. If you open the box and smell burnt ozone or scorched plastic, the logic gates have likely fused. At this point, even if the sauna occasionally works, it is a significant fire hazard.

2 Look for "Puffed" Capacitors

Inspect the cylindrical components (capacitors) on the PCB. The tops should be perfectly flat. If any are bulging, domed, or leaking a crusty residue, they have failed. This is common in saunas older than 5 years due to constant heat expansion and contraction.

3 Terminal Block Scorching

Check where the heater wires plug into the control box. Infrared saunas pull high amperage (up to 15-20A). Over time, loose connections create resistance, leading to black carbon marks on the plastic housing. If you see melting around the heater ports, the board's internal traces are likely damaged beyond repair.