YORK YMC2 — CONDENSER - HIGH PRESSURE CONTACTS OPEN

The control center shows CONDENSER - HIGH PRESSURE CONTACTS OPEN. The manuals print the message in this single form only. It is listed among the safety shutdown messages of the YMC2: the chiller is tripped off by a safety device and can be restarted only after the condition clears and the fault is cleared at the panel.

The electromechanical high pressure safety switch has tripped. This device sits on the condenser shell and opens its contacts when it detects a condenser pressure above its trip setting; that contact opening is what the message reports. The switch recovers by itself — its contacts close again automatically once the condenser pressure falls below the closing threshold that applies to the shell fitted to the chiller.

• The condenser pressure rose above the trip setting of the electromechanical high pressure safety device on the condenser shell — above 204±7 psig on shells with 235 psig DWP, or above 308±7 psig on shells with 350 psig DWP.

1. Determine which condenser shell the chiller has — 235 psig DWP or 350 psig DWP — because the trip and closing pressures differ between the two.
2. Check the condenser pressure against the trip setting for that shell: the contacts open when the device detects pressure greater than 204±7 psig (235 psig DWP shells) or greater than 308±7 psig (350 psig DWP shells).
3. Let the condenser pressure decrease and confirm the contacts have closed — this happens automatically once the pressure is less than 160±10 psig on 235 psig DWP shells, or less than 230±10 psig on 350 psig DWP shells.
4. Press the CLEAR FAULT button once the contacts are closed.
5. Start the chiller.

• Trip point: contacts open at condenser pressure greater than 204±7 psig on shells with 235 psig DWP.
• Trip point: contacts open at condenser pressure greater than 308±7 psig on shells with 350 psig DWP.
• Contacts close again at condenser pressure less than 160±10 psig on 235 psig DWP shells.
• Contacts close again at condenser pressure less than 230±10 psig on 350 psig DWP shells.

The safety device resets itself; no separate action on the switch is described. Once the contacts have closed, clear the fault and restart — the manual states: The chiller can be started after the contacts close and the CLEAR FAULT button is pressed. Until the condenser pressure drops below the closing threshold for the shell fitted (160±10 psig or 230±10 psig), the contacts stay open and the chiller cannot be started.