McQuay PFS Fault Code E26
McQuay PFS Fault Code E26 is a warning alarm indicating: Flow proving fault. The most common causes include Flow proving switch not closing. Estimated repair time: 1-2 hours. This alarm requires immediate attention by a certified HVAC technician.
Alarm Description
Flow proving fault
Brand: McQuay | Model: PFS (Air-Cooled Scroll Chiller) | Code: E26 | Severity: Warning
Observable Symptoms
- Controller displays alarm code and description
- Chiller may be locked out or running in degraded mode
- Alarm indicator light is illuminated on control panel
What to Check First
Before diving into detailed diagnostics, start with this quick first check:
Probable Causes
- Flow proving switch not closing
- Flow switch setpoint too high
- Actual water flow insufficient
Recommended Inspection Steps
- Check flow proving switch operation
- Verify actual water flow rate with meter
- Adjust flow switch setpoint
- Replace flow switch if faulty
Required Tools & Equipment
- Digital multimeter
- OEM service manual
- Safety PPE (gloves, safety glasses)
- 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 PFS codes that may be related:
OEM Service Manual Reference
OEM Reference: McQuay PFS Air-Cooled Scroll Chiller Service Manual. Available through Daikin Applied (formerly McQuay) technical support.
Frequently Asked Questions
What does McQuay PFS fault code E26 mean?
Fault code E26 on a McQuay PFS chiller indicates: Flow proving fault. This is a warning alarm that requires diagnostic attention.
What causes McQuay PFS alarm code E26?
Common causes include: Flow proving switch not closing; Flow switch setpoint too high; Actual water flow insufficient
How do I fix McQuay PFS error code E26?
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.