YORK INTERNATIONAL
176
FORM 160.54-M1(503)
Service Information Letters / Bulletins
Proximity Probe/Limit Switch
Previously, YK chillers equipped with “P” compressors used the High Speed Thrust Bearing Limit Switch and all
other compressors used the Proximity Probe. With Style “F” chillers, only the “J” compressor will use the Prox-
imity Probe. Compressors “G”, “H” and “P” will use the Limit Switch.
In previous Flash memory card versions, the Thrust Bearing Limit Switch indication shows a lit LED for a normal
condition and unlit for a faulted condition. In this version, an unlit LED indicates a normal condition and a lit
LED indicates a faulted condition.
Refrigerant Level Control
In previous Flash Memory Card versions, this control operates as follows:
When the chiller enters “System Run”, if the Refrigerant Level Position is less than the CONTROL
SETPOINT, a linearly increasing ramp limit, called the REFRIGERANT LEVEL TARGET, is applied to the
CONTROL SETPOINT. This ramp limit allows the level to go from the present programmed level to the pro-
grammed CONTROL SETPOINT over a period of 15 minutes. During these 15 minutes, the REFRIGERANT
LEVEL TARGET is used to control the condenser refrigerant level. The Control SETPOINT is then used to
control the refrigerant level for the remainder of chiller run.
In this version, the control will operate as follows:
• While the chiller is stopped, or if the Level Control is disabled, the Refrigerant level “Lower” output is
energized.
• Upon entering chiller Prelube, the Refrigerant Level “Raise” output is energized for the length of the pro-
grammable VALVE PRESET TIME setpoint (0 to 100 seconds; default 50; Service access level). After
pre-positioning, the valve is held in this position until the fi rst 3 minutes of chiller run time have elapsed.
Setting the VALVE PRESET TIME to 0 seconds disables this pre-positioning feature. Setting the Valve
Preset Time to a value greater than 50 seconds has no effect on the Prelube time.
• After 3 minutes of run time, if the Refrigerant Level is less than the CONTROL Setpoint, a linearly in-
creasing ramp limit, called the REFRIGERANT LEVEL TARGET, is applied to the programmed Con-
trol Setpoint. This ramp limit allows the level to go from the present level to the CONTROL SETPOINT
over a period of time programmed as the RAMP-UP TIME Setpoint (3 to 15 minutes; default 8; Service
access level). During this ramp-up period, the REFRIGERANT LEVEL TARGET is used to control
the refrigerant level in the condenser. The CONTROL SETPOINT is used to control the level during the
remainder of chiller run.
• If the VALVE PRESET TIME SETPOINT is set to 0 seconds and the RAMP-UP TIME Setpoint is set
to 15 minutes, Refrigerant Level Control will operate exactly the same as previous Flash Memory Card
versions.
Microboards
Since the new version Flash Memory Card (as described above) is applicable to all YK chillers with any compres-
sor, the Microboard replacement kit 331-01730-604 previously supplied for YK chillers equipped with “P” com-
pressors is no longer required. The standard 331-01730-601 Microboard replacement kit will be supplied when
the 331-01730-604 is ordered.
SI0034 (203) - SOFTWARE ENHANCEMENTS EFFECTIVE AUGUST 2002 (CONT'D)
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