W-402: High cold water temperature

Q: How do I check a W-402 fault?

1. Calculate approach to wet-bulb 2. Inspect nozzles and fill 3. Verify fan speed Safety: Lock out fans before entry; use respiratory protection near drift.

Probable causes

Clogged fill
Poor water distribution
High wet-bulb temperature
Fan running slow

Step-by-step checks

Calculate approach to wet-bulb
Inspect nozzles and fill
Verify fan speed

Safety: Lock out fans before entry; use respiratory protection near drift.

Sample code — verify with the OEM manual for your exact model.

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Frequently asked questions

What does W-402 mean on a Cooling Tower?

W-402 usually indicates: High cold water temperature. Confirm the meaning in the manufacturer's manual for your model.

What causes W-402?

Clogged fill; Poor water distribution; High wet-bulb temperature; Fan running slow.

How do I check a W-402 fault?

Work through the numbered checks above in order, recording readings as you go. Lock out fans before entry; use respiratory protection near drift.

Other Cooling Tower codes

Disclaimer: Fault code information is guidance only. Codes and meanings vary between manufacturers and models — always follow the manufacturer's manual and your site's safety procedures, and use qualified personnel for electrical, pressure, refrigerant and combustion work.