Danfoss E20

What does Danfoss E20 mean?

E20 indicates a fault on the signal from the Pc input on a Danfoss EKC controller, meaning the condensing-pressure transmitter is not providing a valid reading. The controller depends on Pc for its calculations, so this fault interrupts correct regulation. The alarm relay activates at high priority and the controller's LEDs flash to indicate the error.

Symptoms

• Display shows E20 when the alarm is recalled.
• Pc (condensing pressure) reading is missing or out of range.
• Front-panel LEDs flash to signal the regulation error.
• Calculations that depend on condensing pressure are disturbed.

Common causes

• Pressure transmitter on the Pc input has failed.
• Broken or disconnected transmitter signal wiring.
• Transmitter output outside the configured working range set in o20/o21.
• Loss of supply power to the pressure transmitter.

Diagnostic steps

1. 01

   Recall and clear the alarm

   Press the top button to display E20, then press again to cancel the active alarm.

2. 02

   Check the transmitter wiring and supply

   Power down and inspect the Pc transmitter signal wires and its power feed for breaks or loose terminals.

3. 03

   Verify the transmitter range settings

   Confirm the controller's pressure-transmitter range parameters match the fitted transmitter so its output falls inside the expected band.

4. 04

   Test or replace the transmitter

   Measure the transmitter output signal; if it is absent or wrong, replace the Pc pressure transmitter with the correct type.

When to call a professional

Diagnosing E20 involves the high-side pressure transmitter and may require connecting gauges to the refrigerant circuit. A refrigeration technician should verify the transmitter signal, confirm the controller's pressure-range settings, and replace the transmitter if needed. Handling refrigerant pressures and recovering charge require certification, so this is not a task for untrained staff. Correct re-commissioning of the pressure input is essential for safe operation.