Dixell/Copeland F18 Error Code

What does Dixell/Copeland F18 mean?

On the Dixell IC100CX iChill controller, DF18 sets the polarity of the 4-way reversing valve output. Set DF18 to 0 if the reversing valve is energized in cooling mode (active during chiller operation, de-energized during heating). Set DF18 to 1 if the reversing valve is energized in heating mode (active during heat pump operation, de-energized during chiller). This parameter must match the physical valve installed in the refrigerant circuit.

Symptoms

• Unit heating when it should be cooling, or cooling when it should be heating (DF18 inverted for the valve installed).
• Defrost cycle runs in the wrong refrigerant direction — not effective at melting coil ice.
• High discharge pressure in both modes if the valve is in the wrong position for the operating mode.

Common causes

• DF18 set incorrectly for the specific reversing valve model installed (manufacturers differ on convention).
• Replacement reversing valve installed with opposite polarity convention from the original.
• Commissioning error — DF18 not verified during initial setup.

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Diagnostic steps

1. Identify the reversing valve type and polarity convention

   Check the valve manufacturer's datasheet to confirm whether the valve is energized in cooling or heating mode. Common brands (e.g., Parker, Saginomiya, Danfoss) may differ in convention.

2. Check current DF18 setting

   Access the DF sub-menu on the IC100CX. DF18 = 0 means valve ON in cooling; DF18 = 1 means valve ON in heating. Compare to the installed valve specification.

3. Verify 4-way valve operation

   Switch the IC100CX between cooling and heating modes and confirm the reversing valve solenoid energizes and de-energizes at the correct times. Use a voltmeter at the valve terminals to verify energization.

4. Correct DF18 if inverted

   If the valve is energizing in the wrong mode, change DF18 from 0 to 1 or vice versa. After changing, run both heating and cooling modes to confirm correct behavior.

5. Confirm defrost cycle direction

   Manually initiate a defrost cycle and confirm the unit switches to the correct mode for coil heating (typically the heating refrigerant circuit direction). Verify the outdoor coil temperature rises during defrost.

When to call a professional

If the reversing valve is mechanically stuck in one position — neither energizing nor de-energizing correctly — a licensed refrigeration technician must diagnose whether the solenoid coil has failed or the valve slide is seized. Valve replacement requires refrigerant system recovery.