W-405: High conductivity

Q: How do I check a W-405 fault?

1. Check conductivity controller 2. Test make-up water 3. Adjust blowdown with water treatment supplier Safety: Lock out fans before entry; use respiratory protection near drift.

Probable causes

Low blowdown
Make-up quality change

Step-by-step checks

Check conductivity controller
Test make-up water
Adjust blowdown with water treatment supplier

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

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

Ask the expert on WhatsApp

Frequently asked questions

What does W-405 mean on a Cooling Tower?

W-405 usually indicates: High conductivity. Confirm the meaning in the manufacturer's manual for your model.

What causes W-405?

Low blowdown; Make-up quality change.

How do I check a W-405 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.