Trane RTHB Fault Code 390
Trane RTHB Fault Code 390 is a warning alarm indicating: Communication Lost - Main to Starter. The most common causes include CCN cable fault. Estimated repair time: 1-3 hours (requires board replacement, configuration, and commissioning). This alarm requires immediate attention by a certified HVAC technician.
Alarm Description
Communication Lost - Main to Starter
Brand: Trane | Model: RTHB (Helical Rotary Chiller (Water-Cooled)) | Code: 390 | Severity: Warning
Observable Symptoms
- Controller display shows communication error or blank screen
- BAS/EMS system shows chiller as offline or in alarm state
What to Check First
Before diving into detailed diagnostics, start with this quick first check:
Probable Causes
- CCN cable fault
- Starter board power failure
- Address conflict
Recommended Inspection Steps
- Check cable
- Verify power
- Check addresses
- Replace board
Required Tools & Equipment
- Safety PPE (gloves, safety glasses, face shield)
- Wire tracing and continuity tester
Estimated Repair Time
1-3 hours (requires board replacement, configuration, and commissioning)
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 RTHB codes that may be related:
OEM Service Manual Reference
OEM Reference: Trane RTHB Helical Rotary Chiller Service Manual. Available through Trane Commercial support.
Frequently Asked Questions
What does Trane RTHB fault code 390 mean?
Fault code 390 on a Trane RTHB chiller indicates: Communication Lost - Main to Starter. This is a warning alarm that requires diagnostic attention.
What causes Trane RTHB alarm code 390?
Common causes include: CCN cable fault; Starter board power failure; Address conflict
How do I fix Trane RTHB error code 390?
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.