This article covers the following water‑management related fault codes on Climate Wizard CW‑H units:

• Fault Code 2 (FC2) – Failure to detect water at Low Probe
• Fault Code 3 (FC3) – Failure to detect water at High Probe
• Fault Code 4 (FC4) – Failure to clear Low Probe during drain
• Fault Code 5 (FC5) – Water detected at High Probe but not Low Probe

These faults all relate to the Water Management System and should be diagnosed together, as they share common components, timing logic, and root causes.

Manual Reference: Fault Code Descriptions — p.29

How CW‑H Water Level Detection Works

Climate Wizard CW‑H coolers use a 3‑pin water management probe installed in the tank to detect both water level and water salinity.

The probe provides two level signals:

• Low Probe – Confirms minimum safe water level for pump operation
• High Probe – Confirms the tank has reached full operational level

The PLC relies on these signals to:

• open and close the inlet solenoid valve
• permit or inhibit pump operation
• control drain and salinity cycles
• validate correct tank fill and empty sequences

If the probe does not change state within defined time limits, the PLC assumes unsafe water conditions and generates Fault Codes 2–5, shutting the cooler down.

Manual References:
Water Management System — pp.16–17
Water Management Probe — p.39

⚠️ Water Supply Requirements (Page 15)

This section is mandatory reading before diagnosing FC2 or FC3.

A very high percentage of FC2–FC5 faults are caused by water supplies that do not meet the CW‑H installation specifications, even though water is visibly connected and flowing.

The CW‑H water management logic is time‑based. Slow, restricted, unstable, or poorly isolated supplies will cause fill and drain faults.

✅ CW‑H Water Supply Specifications (From Manual Page 15)

For correct operation, each CW‑H unit must have:

• Water connection size:
  ½″ BSP (permanent connection – not hose‑fed)
• Minimum static pressure:
  100 kPa (15 psi)
• Maximum static pressure:
  800 kPa (115 psi)
• Minimum flow rate:
  10 L/min per cooler
• Recommended flow rate:
  20 L/min per cooler
• Maximum water temperature:
  40 °C
• Water quality:
  Potable water suitable for human consumption
• Minimum water salinity:
  > 100 µS/cm
• Minimum filtration:
  500‑micron inlet filtration

⚠️ Supplies that fall outside any of these limits are considered non‑compliant and can directly cause FC2–FC5.

✅ Isolation & Valve Requirements

Incorrect isolation valves are a known cause of repeat FC2 and FC3 faults.

• Only ball valves or approved non‑return (check) valves are permitted for water isolation
• Gate valves, stop cocks, globe valves, or multi‑turn valves must NOT be used

Incorrect valve types can:

• shed debris into the line
• create pressure instability
• introduce back‑pressure
• cause the inlet solenoid valve to jam or stick partially open/closed

These conditions frequently result in:

• slow filling
• incomplete tank fills
• FC2 or FC3 repeating after reset

✅ Additional Installation Requirements That Affect FC2–FC5

• A manual isolation valve must be installed adjacent to the cooler
• A pressure regulator must be installed if supply exceeds 800 kPa
• If a non‑return valve is used, a pressure relief valve is recommended
• Pipework must be flushed before connection
• Water hammer must be addressed if present
• Drain‑down capability must be provided in freezing climates

Strong Diagnostic Rule (Field Proven)

If the tank cannot reliably fill from empty to the high probe within the allowed time,
 you do not yet have a probe fault – you have a water supply problem.

Fault Code 2 – Failure to Detect Water at Low Probe

Fault Description

FC2 occurs when no water is detected at the low probe within 20 minutes after the inlet solenoid valve is commanded open.

The PLC assumes water is not entering the tank and shuts the cooler down.

Manual Reference: p.29

Common Causes 

• Water supply isolated or undersized
• Pressure below 100 kPa at the unit
• Inlet strainer partially blocked (< 500 µm effective)
• Incorrect isolation valve type restricting solenoid
• Solenoid valve not opening
• Drain valve stuck open
• Cooler out of level
• Fouled or contaminated probe

Troubleshooting Procedure

1. Confirm isolation valve type (ball or non‑return only)
2. Verify pressure and flow at the cooler
3. Inspect and clean inlet strainer
4. Confirm solenoid valve opens during fill
5. Verify drain valve fully closes
6. Observe physical water entry into tank
7. Clean water management probe
8. Confirm cooler is level

⚠️ Do not replace probes or PCBA until water supply compliance is confirmed.

Fault Code 3 – Failure to Detect Water at High Probe

Fault Description

FC3 occurs when water is detected at the low probe, but not at the high probe within 30 minutes.

The tank is filling but not reaching the required full level.

Manual Reference: p.29

Common Causes

• Flow rate below specification
• Pressure regulators set too low
• Blocked or restrictive isolation valves
• Partial drain valve leakage
• Multiple coolers filling on a shared supply
• Probe contamination

Troubleshooting Procedure

1. Confirm supply satisfies Page 15 specifications
2. Inspect isolation valve type and operation
3. Measure or verify flow rate
4. Inspect strainer and solenoid valve
5. Check drain valve sealing
6. Observe tank fill time and level rise
7. Clean and inspect probe

? Repeated FC3 is almost always a supply or drain issue.

Fault Code 4 – Failure to Clear Low Probe During Drain

Fault Description

FC4 occurs when water is still detected at the low probe 20 minutes after a drain cycle begins.

This indicates the tank is not draining correctly.

Manual Reference: p.29

Common Causes

• Blocked or undersized drain pipework
• Back‑pressure from downstream plumbing
• Drain valve failure
• Poor drain installation
• Fouled probe giving false “wet” signal

Troubleshooting Procedure

1. Confirm drain valve opens when commanded
2. Verify strong, continuous drain discharge
3. Inspect drain line for restrictions or traps
4. Confirm drain installation meets requirements
5. Clean probe
6. Perform full manual drain and observe empty tank

Fault Code 5 – Water Detected at High Probe but Not Low Probe

Fault Description

FC5 occurs when water is detected at the high probe, but not at the low probe.

This is physically impossible in normal operation and indicates invalid probe readings.

Manual Reference: p.29

Root Cause

• Probe pins contaminated or scaled
• Moisture bridging between probe pins
• Probe not clipped correctly into bracket

Troubleshooting Procedure

1. Remove and clean probe thoroughly
2. Inspect pins for build‑up or corrosion
3. Confirm correct seating and alignment
4. Reinstall and reset fault