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Guided Diagnostics
5-10 min · 7 steps

Danfoss AK-SC 355: Stepper Valve / Output Fault

Diagnose an AK-SC 355 variable output / stepper valve that isn't controlling.

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First step

Rescan the valve module — is it online to the AK-SC?

No — module offline
Yes — module online

This is a preview of the first step. Run the full interactive diagnostic free — it walks you all the way to the likely root cause.

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For qualified refrigeration technicians. Always follow manufacturer procedures and local codes. R-290 (propane) and other flammable refrigerants require A3-rated tools and safety practices.