Danfoss A43

What does Danfoss A43 mean?

A43 is a step-motor fault on a Danfoss EKC valve controller, reported by the EKC 313 as an output or phase error. The controller has detected a problem driving the stepper-motor expansion valve (such as an ETS or CCM valve), so it can no longer position the valve reliably. The alarm relay activates at high priority and regulation of the valve opening degree is affected.

Symptoms

• Display shows A43 when the alarm is recalled.
• Stepper expansion valve does not move to its commanded opening degree.
• Front-panel LEDs flash to indicate the regulation error.
• Superheat or capacity regulation is erratic because valve control is lost.

Common causes

• Open or short on one of the stepper-motor phases.
• Broken or miswired valve motor cable.
• Failed valve coil or stepper motor.
• Valve type parameter (n03) set to the wrong valve model.

Diagnostic steps

1. 01

   Recall the alarm code

   Press the top button to display A43, then press again to cancel the active alarm.

2. 02

   Check the valve motor wiring

   Power down and inspect the stepper-motor cable and terminals for breaks, shorts, or loose connections on each phase.

3. 03

   Verify the valve type setting

   Confirm parameter n03 matches the installed valve model (for example ETS 12,5/25, ETS 50, ETS 250) so the controller drives it correctly.

4. 04

   Test or replace the valve motor

   Measure the coil phases; if a phase is open or shorted, replace the valve motor or coil with the correct part.

When to call a professional

A step-motor fault leaves the expansion valve uncontrolled, which can flood or starve the evaporator and stress the compressor. A refrigeration technician should test each motor phase, confirm the valve-type parameter, and replace the valve or coil if a phase has failed. Replacing an electronic expansion valve can require refrigerant handling and recalibration, so it should be done by certified staff.