Trane RTAC Fault Code BB
Trane RTAC Fault Code BB is a warning alarm indicating: Motor Current Overload - Compressor 2A. The most common causes include Compressor 2A motor bearing failure. Estimated repair time: 1-2 hours. This alarm requires immediate attention by a certified HVAC technician.
Alarm Description
Motor Current Overload - Compressor 2A
Brand: Trane | Model: RTAC (Screw Compressor Chiller) | Code: BB | Severity: Warning
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:
Probable Causes
- Compressor 2A motor bearing failure
- Voltage imbalance on circuit 2
- Liquid floodback to compressor 2A
- Mechanical overload
Recommended Inspection Steps
- Measure motor current on compressor 2A
- Check voltage balance on circuit 2
- Verify superheat on circuit 2
- Inspect compressor 2A
Required Tools & Equipment
- Clamp-on ammeter
- Digital multimeter
- 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 Trane service representative for warranty-covered repairs
Related Fault Codes
Other Trane RTAC codes that may be related:
OEM Service Manual Reference
OEM Reference: Trane RTAC Air-Cooled Rotary Screw Chiller Service Manual (SVR-SVN001-EN). Available through Trane Commercial support.
Frequently Asked Questions
What does Trane RTAC fault code BB mean?
Fault code BB on a Trane RTAC chiller indicates: Motor Current Overload - Compressor 2A. This is a warning alarm that requires diagnostic attention.
What causes Trane RTAC alarm code BB?
Common causes include: Compressor 2A motor bearing failure; Voltage imbalance on circuit 2; Liquid floodback to compressor 2A
How do I fix Trane RTAC error code BB?
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 Trane service representative.