CriticalCO₂ Transcritical
CO2 Standstill / Off-Cycle Pressure Rise
With the rack off, warming CO2 raises system pressure toward the relief setting; the standstill unit must hold pressure down or refrigerant is lost.
Symptoms
- System pressure climbing while the rack is off (power loss / long fault)
- Standstill condensing unit / auxiliary not running
- Relief valve lifting, losing CO2 charge
- High low-side standstill pressure alarm (~ approaching 1305 psi low-side relief)
Unlock the full fix
Likely causes, step-by-step troubleshooting & safety notes
Get the complete diagnostic guide for CO2 Standstill / Off-Cycle Pressure Rise — plus the full fault library, guided diagnostics, AI + photo diagnose, and CO₂ & R-290 reference. Start free, no card needed.
Related faults