FC9 – PLC Expansion Module Failure (CW‑80 / CW‑80S)

Applicable Models: CW‑80, CW‑80S

Reference: 859723-G - CW-80 Multi-Magic - Install and Operation Manual (English) 

Fault Code Description:
The PLC has lost communication with the Water Manager Expansion Module (PCBA).
(Manual: Fault Code Table – p.31)

When FC9 is active, technicians may also see FC7 (Supply Motor Error) and FC13 (Exhaust Motor Error) because the motor I/O signals flow through the same expansion module.
(FC7/13 descriptions – p.31)

1. Symptoms

• FC9 logged on PLC
• FC7 and FC13 often appear simultaneously across all motors
• No fan activity or incomplete status on Monitor screens
• Water Manager PCBA LED flashing RED indicating comms fault
  (LED State Table – p.30)

2. Likely Causes

1. Loose communication cable between PLC and Expansion Module
2. Water Manager PCBA not powered (loss of 24 VAC)
3. Faulty Water Manager PCBA
4. Faulty PLC communication interface

3. Step‑by‑Step Troubleshooting

Step 1 — Check Communication Cable (On‑Site Visual Inspection)

• Reseat the comms cable at both ends (PLC and PCBA).
• Check for loose connectors, bent/damaged pins, corrosion, moisture or dust.
  (Fault Code 9 Remedy – p.31)
  (Location of PCBA shown in “Cooler Control Components” – p.19)

Step 2 — Check Water Manager PCBA LED State

LED meanings (Water Manager LED Table – p.30):

• Flashing GREEN → Normal
• Flashing RED → Communication fault
• Solid GREEN (first 30–45s) → Startup period

If Flashing RED → PLC and module are not communicating.

Step 3 — Power‑Cycle the Cooler

• Isolate mains supply, wait 10–15 seconds, restore.
  (Active faults clear on power cycle – p.30)

FC9 can occur when the PLC boots before the expansion module fully initialises.

Step 4 — Verify 24 VAC Power to Expansion Module

The Water Manager PCBA requires a stable 24 VAC supply via TF1/TF2.
(24 VAC supply details – p.16)

Check:

• Transformer outputs
• Low‑voltage fuses
• Burnt smell or heat damage on PCBA

Loss of 24 VAC will cause FC9 and secondary FC7/FC13.

Step 5 — Use PLC Screens to Confirm Expansion Module Status

Monitor → Fan Screen

If all motors show 0V or FAULT, the module is likely offline.
(Monitor screen details – p.21)

Active Faults Screen

If FC7/FC13 appear across all fans → Comms loss, not individual motors.
(Fault behaviors – p.31)

Step 6 — Use the TEST MENU to Directly Command the Fans

Path: SETUP → SERVICE → TEST MENU
(TEST Menu instructions – p.38)

Test:

• SpFAN (Supply Fans)
• ExhFAN (Exhaust Fans)

Interpret results:

• Fans run normally in TEST
  → Module is powered and responding → issue is PLC‑module comms layer
• Fans do NOT respond in TEST
  → Module is not responding → likely failed module or no 24 VAC supply

4. Determining the Root Cause

A. Expansion Module (Water Manager PCBA) is likely faulty if:

• PCBA LED = Flashing RED
• 24 VAC confirmed present
• TEST MENU cannot drive fans
• FC7/FC13 present on ALL motors
• Replacing comms cable has no effect

B. PLC is likely faulty if:

• Expansion PCBA LEDs indicate normal operation
• Comms cable replaced/tested OK
• TEST MENU still cannot communicate
• PLC’s red fault LED continues to display FC9 after power cycling
  (PLC LEDs – p.20)

5. Recommended Corrective Actions

1. Reseat or replace PLC ↔ PCBA comms cable
2. Restore/repair 24 VAC supply (TF1/TF2, wiring, fuses)
3. Replace Water Manager Expansion Module (most common fix)
4. Replace PLC if module replacement does not resolve FC9

6. Manual Page Reference Summary