McQuay ALS Fault Code E11

E11
Overcurrent protection
Critical
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

McQuay ALS Fault Code E11 is a critical safety alarm indicating: Overcurrent protection. The most common causes include Motor overload. Estimated repair time: 45-90 minutes. This alarm requires immediate attention by a certified HVAC technician.

Alarm Description

Overcurrent protection

Brand: McQuay  |  Model: ALS (Air-Cooled Screw Chiller)  |  Code: E11  |  Severity: Critical

Observable Symptoms

  • Compressor motor starter or VFD shows overload trip indication
  • Motor current reading exceeds nameplate FLA on ammeter
  • Compressor may hum but not start, or starts and trips quickly

What to Check First

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

Quick Start: Measure current

Probable Causes

  • Motor overload
  • Short circuit
  • Contactor welded

Recommended Inspection Steps

  1. Measure current
  2. Check winding resistance
  3. Inspect contactor

Required Tools & Equipment

  • Clamp-on ammeter
  • Digital multimeter
  • 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 McQuay service representative for warranty-covered repairs

Related Fault Codes

Other McQuay ALS codes that may be related:

E01E02E03E04E05

OEM Service Manual Reference

OEM Reference: McQuay ALS Air-Cooled Screw Chiller Service Manual. Available through Daikin Applied technical support.

Frequently Asked Questions

What does McQuay ALS fault code E11 mean?

Fault code E11 on a McQuay ALS chiller indicates: Overcurrent protection. This is a critical safety alarm that requires diagnostic attention.

What causes McQuay ALS alarm code E11?

Common causes include: Motor overload; Short circuit; Contactor welded

How do I fix McQuay ALS error code E11?

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 McQuay 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 McQuay ALS service procedures.