Select your chiller symptom to get recommended inspection steps and diagnostic procedures
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Click symptom links to jump to related fault code pages for specific manufacturers
| Symptom | First Check | Common Cause | Action & Related Codes |
|---|---|---|---|
| Chiller won't start | Control panel power | Tripped safety device | Check all safety interlocks, reset and investigate. See Carrier 30XA Code 41, Trane RTAC FD |
| High head pressure | Condenser cleanliness | Fouled condenser / poor airflow | Clean condenser, verify fan operation. See Trane RTAC F5, McQuay WMC E01 |
| Low suction pressure | Refrigerant charge | Low charge / expansion valve issue | Check subcooling, inspect TXV operation. See McQuay WMC E02, Daikin EWAD H2 |
| Compressor overload | Motor current | Voltage imbalance / bearing wear | Check phase balance, inspect bearings. See Trane RTAC BA, Daikin EWAD E3 |
| Oil pressure low | Oil level sight glass | Low oil / clogged filter | Check oil level, replace filter. See Carrier 30XA Code 68, McQuay WMC E12 |
| Freeze protection trip | Water flow and temperature | Low flow / low setpoint | Verify pump flow, raise setpoint above 40F. See York YVAA EB, Lennox SCA E08 |
| Communication fault | Network cable | Cable damaged / controller offline | Check connections, verify controller status. See Trane RTHD Code 398, Lennox SCA E14 |
| Modular chiller module fault | Module communication | Inter-module cable / controller offline | Check inter-module cables, verify module status. See ClimaCool WMC E05, Multistack ASP E06 |
| Module isolation valve fault | Valve motor & position sensor | Valve motor failure / stuck | Check valve motor, verify position sensor. See Multistack MSW E13, ClimaCool ACC E13 |
| VSD compressor fault | VSD communication & temperature | VSD communication / over-temp / hardware | Check VSD fault codes, verify cooling. See Carrier 23XRV VSD1, York YK E3 |