McQuay ALS Fault Code E12

E12
Oil pressure low
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 E12 is a critical safety alarm indicating: Oil pressure low. The most common causes include Oil pump wear. Estimated repair time: 45-90 minutes. This alarm requires immediate attention by a certified HVAC technician.

Alarm Description

Oil pressure low

Brand: McQuay  |  Model: ALS (Air-Cooled Screw Chiller)  |  Code: E12  |  Severity: Critical

Observable Symptoms

  • Oil sight glass shows low level or empty
  • Compressor may make unusual noise from lack of lubrication
  • Oil pressure differential alarm may also be active

What to Check First

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

Quick Start: Check oil level

Probable Causes

  • Oil pump wear
  • Filter clogged
  • Low oil level

Recommended Inspection Steps

  1. Check oil level
  2. Replace filter
  3. Measure pump pressure

Required Tools & Equipment

  • Oil level sight glass inspection tool
  • 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 E12 mean?

Fault code E12 on a McQuay ALS chiller indicates: Oil pressure low. This is a critical safety alarm that requires diagnostic attention.

What causes McQuay ALS alarm code E12?

Common causes include: Oil pump wear; Filter clogged; Low oil level

How do I fix McQuay ALS error code E12?

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.