Danfoss E25

High

AK-CC 550A — S3 sensor error (return air)

Danfoss E25: S3 sensor error (return air) This fault noticeably affects operation.

Possible causes

Sensor S3 defective, cable break or short circuit
Wrong sensor type configured (Pt/PTC/NTC mismatch)

Check steps

Measure resistance/signal of S3 and compare against the configured sensor type
Check S3 wiring, replace sensor if needed; use U12 to verify

Affected parts

S3 sensor (return air)
Sensor cable/connector

Safety note

De-energize before replacing the sensor.

Source: Danfoss resmi servis kilavuzu (bagimsiz cift-dogrulandi) — Danfoss "Pocket Guide, AK-CC 550A Service Guide" (ADAP-KOOL Refrigeration Control System), document no. AX278928624187en-000101, © Danfoss 2018.08, p.2 (of 2). Alarm Codes table lists "E25 S3 Sensor Error". Sensor/Relay Checks table lists "U12 S3 Sensor (Return Air)". Source PDF: https://assets.danfoss.com/docume…

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

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