On the display
The panel shows SYS X HPCO FAULT; X is the number of the system that tripped. The message carries a status word where the manuals print YYYYYYY: it reads either FAULT or LOCKOUT. Note which word is displayed, because the two states come back differently — a FAULT clears itself through the anti-recycle timer, while a LOCKOUT does not restart until the operator clears it (see Reset).
What it means
This is a hardware high pressure cutout fault. The mechanical HPCO protects the system from dangerously high discharge pressure: when it trips, its contacts open and the system shuts down immediately. Unlike most system faults, it does not wait the typical 3 seconds. The HPCO is wired in series with the VSD Run Signal, so it is checked only while the system is running.
Why it appears
- The mechanical high pressure cutout contacts open. The cutout opens at 297 +/- 8 PSIG; it closes again at 230 +/- 10 PSIG.
Setpoints and thresholds
- HPCO opens (trips) at 297 +/- 8 PSIG.
- HPCO closes (resets) at 230 +/- 10 PSIG.
- Auto-restart after the 120-second anti-recycle timer.
- Lockout after 3 faults on the same system within 90 minutes.
Reset and restart
After a normal FAULT the system comes back on its own: it restarts when the 120-second anti-recycle timer times out, provided the cutout has closed again (it resets at 230 +/- 10 PSIG). If the display shows LOCKOUT — which happens after 3 faults on the same system within 90 minutes — the system will not restart by itself. The manuals state the system will not restart until the operator clears the fault using the keypad
, and describe the lockout as lockout cleared by cycling the system switch OFF and ON
.
Questions engineers ask
What does SYS X HPCO FAULT mean on a YORK YCAV?
It is a hardware high pressure cutout fault: the mechanical HPCO opened to protect the system from dangerously high discharge pressure. The shutdown is immediate and does not wait the 3 seconds typical of most system faults.
At what pressure does the HPCO trip and reset?
The mechanical cutout opens at 297 +/- 8 PSIG and closes again at 230 +/- 10 PSIG. It is wired in series with the VSD Run Signal, so it is checked only while the system is running.
Will the chiller restart by itself after an HPCO fault?
Yes, after a normal FAULT: the system restarts when the 120-second anti-recycle timer times out. Only a LOCKOUT — 3 faults on the same system within 90 minutes — waits for the operator.
How do I clear an HPCO LOCKOUT?
The system will not restart until the operator clears the fault using the keypad; the manual describes the lockout as cleared by cycling the system switch OFF and ON.
Messages next to this one
The same message on other models
Source
Written from the manufacturer's manuals for the YORK YCAV; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YCAV messages: fault codes · YORK YCAV documentation · YORK manuals