Carrier AquaSnap Chiller Fault Codes — Quick Reference
Carrier AquaSnap 30RB (air-cooled liquid chiller) and 30RQ (heat pump) use the Pro-Dialog+ or i-Vue controller. Alarms appear as codes with descriptions on the controller display.
| Alarm Code | Meaning | Quick Fix |
|---|---|---|
| A1 — Low Pressure | Suction pressure safety | Check refrigerant charge and evap flow |
| A2 — High Pressure | Discharge pressure safety | Check fans and condenser coil |
| A3 — Low LWT | Leaving water temp below limit | Check flow and freeze protection |
| A4 — Compressor Overload | Compressor motor tripped | Check current, voltage, and contacts |
| A5 — High Discharge Temp | Compressor discharge too hot | Check charge and condenser |
| A6 — Loss of Flow | Chilled water flow lost | Check pump, filter, and flow switch |
| A7 — Loss of Phase | Phase loss detected | Check electrical supply |
| A8 — High Motor Temp | Compressor thermal protection | Check voltage and cooling |
Most Common Faults
A1 — Low Pressure Alarm
Low refrigerant suction pressure is the top alarm on AquaSnap chillers. Check chilled water flow rate first — a closed pump valve, blocked strainer, or pump failure causes the evaporator to starve. If flow is confirmed, check the refrigerant charge.
A2 — High Pressure Alarm
High discharge pressure trips are common in summer. Check: all condenser fans are running (visually verify), condenser coil is clean, and ambient temperature is within the unit’s rating. 30RB units use multiple fans — if one fan fails, high pressure can follow on hot days.
A6 — Loss of Flow
The flow switch in the evaporator has opened. Check: pump breaker, pump rotation (check at VFD if applicable), strainer, and flow switch condition. A dirty flow switch can give false trips.
Pro-Dialog+ Controller Navigation
- ALARM button → shows active alarms and history
- STATUS button → live operating data (pressures, temperatures, current)
- SETPOINTS → operating limits configuration
i-Vue Controller
The i-Vue touchscreen shows alarm icons in the top bar. Tap the icon to see fault description. The event history shows the last 200 events with timestamps.
Parts Often Needed
| Part | Notes |
|---|---|
| Condenser fan motor | Amazon | Replace on A2 high pressure faults |
| Flow switch | Amazon | Replace on repeated A6 faults |
| Refrigerant charge | Amazon | After leak repair |
| High pressure switch | Amazon | Replace if repeatedly tripping |
Jump to Fix
- A1 low pressure → Check chilled water flow → Check refrigerant charge → Inspect evap
- A2 high pressure → Verify all fans running → Clean condenser coil
- A6 loss of flow → Check pump → Inspect strainer → Test flow switch
When to Call a Pro
Carrier (Carrier Commercial Service) handles refrigerant work and compressor replacement. Call 1-800-379-6484 for service support.