McQuay ALS Fault Code E02
McQuay ALS Fault Code E02 is a warning alarm indicating: Compressor low pressure protection. The most common causes include Low refrigerant charge. Estimated repair time: 1-2 hours. This alarm requires immediate attention by a certified HVAC technician.
Alarm Description
Compressor low pressure protection
Brand: McQuay | Model: ALS (Air-Cooled Screw Chiller) | Code: E02 | Severity: Warning
Observable Symptoms
- Suction pressure gauge reads below normal operating range
- Compressor may short cycle or run continuously without cooling
- Frost may appear on suction line or evaporator
What to Check First
Before diving into detailed diagnostics, start with this quick first check:
Probable Causes
- Low refrigerant charge
- Expansion valve issue
- Evaporator water flow low
- Fouled evaporator
Recommended Inspection Steps
- Check charge
- Inspect expansion valve
- Measure water flow
- Clean evaporator
Required Tools & Equipment
- Coil cleaning brush and coil cleaner
- PT chart for refrigerant type
- Safety PPE (gloves, safety glasses, face shield)
Estimated Repair Time
1-2 hours
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:
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 E02 mean?
Fault code E02 on a McQuay ALS chiller indicates: Compressor low pressure protection. This is a warning alarm that requires diagnostic attention.
What causes McQuay ALS alarm code E02?
Common causes include: Low refrigerant charge; Expansion valve issue; Evaporator water flow low
How do I fix McQuay ALS error code E02?
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.