Danfoss E30

What does Danfoss E30 mean?

On the Danfoss ERC 21X controller, E30 means the Sc (condenser) sensor is defective or its electrical connection is lost. The controller monitors condenser temperature to protect the compressor and trigger condenser alarms, so losing this sensor removes that protection. The display alternates between the air temperature and the active alarm codes, and the alarm relay is activated.

Symptoms

• Display alternates between air temperature and the code E30.
• Condenser temperature reading is missing or faulted.
• Condenser high-temperature protection (A61/A80) cannot operate.
• Alarm relay is activated.

Common causes

• Condenser (Sc) sensor is defective.
• Electrical connection to the condenser sensor is lost or broken.
• Sensor cable damaged near the hot condenser section.
• Loose or corroded terminal at the sensor input.

Diagnostic steps

1. 01

   Confirm the alarm source

   Read the display alternating between air temperature and E30 to identify the condenser sensor as the fault.

2. 02

   Inspect the condenser sensor wiring

   Power down and check the Sc cable and terminals, allowing for heat damage near the condenser.

3. 03

   Measure the sensor

   Disconnect Sc and measure its resistance against the fitted sensor type; an open or shorted reading confirms a failed sensor.

4. 04

   Replace the condenser sensor

   Fit a new sensor of the correct type, mount it as before on the condenser, and confirm E30 clears on power-up.

When to call a professional

Without the condenser sensor the controller cannot warn of a blocked or overheating condenser, which risks compressor damage. If E30 persists after replacement, a refrigeration technician should verify the sensor type, mounting, and the condenser-alarm settings. Trained diagnosis ensures condenser protection is restored and that any underlying overheating cause, such as restricted airflow, is also addressed.