Lennox LSB Fault Code E05

E05
Evaporator water flow fault
Warning
SAFETY WARNING: Commercial chillers contain high-pressure refrigerants and high-voltage electrical components (208V-4160V). Only EPA Section 608 certified technicians should perform diagnostic work. Always follow lockout/tagout procedures and wear appropriate PPE. Do not attempt repairs without proper training and equipment.
AI Summary

Lennox LSB Fault Code E05 is a warning alarm indicating: Evaporator water flow fault. The most common causes include Pump stopped. Estimated repair time: 45-90 minutes. This alarm requires immediate attention by a certified HVAC technician.

Alarm Description

Evaporator water flow fault

Brand: Lennox  |  Model: LSB (Water-Cooled Chiller)  |  Code: E05  |  Severity: Warning

Observable Symptoms

  • Water flow indicator shows zero or low flow
  • Differential pressure across evaporator or condenser is low
  • Pump may not be running or making abnormal noise

What to Check First

Before diving into detailed diagnostics, start with this quick first check:

Quick Start: Verify pump

Probable Causes

  • Pump stopped
  • Flow switch fault
  • Strainer clogged

Recommended Inspection Steps

  1. Verify pump
  2. Check flow switch
  3. Clean strainer

Required Tools & Equipment

  • Coil cleaning brush and coil cleaner
  • Safety PPE (gloves, safety glasses, face shield)

Estimated Repair Time

45-90 minutes

When to Call a Professional

  • If the fault persists after completing all recommended inspection steps
  • If you observe unusual noises, vibrations, or oil leaks from the compressor
  • If refrigerant charge levels are outside OEM specifications and EPA-certified recovery is needed
  • If electrical measurements show voltage imbalance greater than 2% between phases
  • If the fault recurs immediately after reset, indicating an unresolved safety condition
  • Contact an authorized Lennox service representative for warranty-covered repairs

Related Fault Codes

Other Lennox LSB codes that may be related:

E01E02E03E04E06

OEM Service Manual Reference

OEM Reference: Lennox LSB Chiller Service Manual. Available through Lennox Commercial technical support.

Frequently Asked Questions

What does Lennox LSB fault code E05 mean?

Fault code E05 on a Lennox LSB chiller indicates: Evaporator water flow fault. This is a warning alarm that requires diagnostic attention.

What causes Lennox LSB alarm code E05?

Common causes include: Pump stopped; Flow switch fault; Strainer clogged

How do I fix Lennox LSB error code E05?

Follow the recommended inspection steps below. Start with the quick check, then proceed through each step. If the fault persists after all steps, contact an authorized Lennox service representative.

Disclaimer: All lookup data is for reference only. Do not use this information to replace certified professional HVAC technician judgment. Always refer to original OEM official service manual for Lennox LSB service procedures.