Cooling Operation Errors - York ZE Series Instruction Manual

Cooling Operation Errors

Each cooling system is monitored for operation outside of the
intended parameters. Errors are handled as described below. All
system errors override minimum run times for compressors.
High-Pressure Limit Switch
During cooling operation, if a high-pressure limit switch opens,
the UCB will de-energize the compressor, initiate the ASCD
(Anti-short cycle delay), and stop the condenser fan. If the call
for cooling is still present at the conclusion of the ASCD, the
UCB will re-energize the compressor.
Should a high-pressure switch open three times within two
hours of operation, the UCB will lock-out the associated
compressor and flash a code on the Simplicity Lite Control (see
Table 31) or sent error message to the LCD Smart
Equipment™ Control.
Low-Pressure Limit Switch
The low-pressure limit switch is not monitored during the initial
30 seconds of a cooling system's operation. For the following
30 seconds, the UCB will monitor the low-pressure switch to
ensure it closes. If the low-pressure switch fails to close after
the 30-second monitoring phase, the UCB will de-energize the
compressor, initiate the ASCD, and stop the condenser fan.
Once the low-pressure switch has been proven (closed during the
30-second monitor period described above), the UCB will monitor
the low-pressure limit switch for any openings. If the low-pressure
switch opens for greater than 5 seconds, the UCB will de-energize
the compressor, initiate the ASCD, and stop the condenser fan.
If the call for cooling is still present at the conclusion of the
ASCD, the UCB will re-energize the compressor.
Should a low-pressure switch open three times within one hour
of operation, the UCB will lock-out the compressor and flash a
code on the Simplicity Lite Control (Table 31) or sent error
message to the LCD Smart Equipment™ Control.
Freezestat (Simplicity Lite Control)
During cooling operation, if a freezestat opens, the UCB will de-
energize the compressor, initiate the ASCD, and stop the
condenser fan. If the call for cooling is still present at the
conclusion of the ASCD, the UCB will re-energize the halted
compressor.
Should a freezestat open three times within two hours of
operation, the UCB will lock-out the associated compressor and
flash a code on the Simplicity Lite Control (Table 31).
Evaporator Low Limit (Smart Equipment™ Control)
During cooling operation, if the Evaporator Low Limit Sensor
(EC1) (Located on the Suction Line at the Evaporator Coil.)
detects a temperature below 26 Deg. F (default), the UCB will
de-energize the compressor, initiate the ASCD, and stop the
condenser fan. If the call for cooling is still present at the
conclusion of the ASCD, the UCB will re-energize the halted
compressor.
Johnson Controls Ducted Systems
Should the evaporator low limit sensor (EC1) detect a
temperature below 26°F three times within two hours of
operation, the UCB will lock-out the associated compressor and
flash an error message.
Low Ambient Cooling (Simplicity Lite Control)
To determine when to operate in low ambient mode, the UCB
has a pair of terminals connected to a temperature-activated
switch set at 45ºF. When the low ambient switch is closed and
the thermostat is calling for cooling, the UCB will operate in the
low ambient mode.
Low ambient mode operates the compressors in this manner:
10 minutes on, 5 minutes off. The indoor blower is operated
throughout the cycle. The 5-minute off period is necessary to
defrost the indoor coil.
Low ambient mode always begins with compressor operation.
Compressor minimum run time may extend the minutes of
compressor operation.
When operating in low ambient mode, the UCB will not lockout
the compressors due to a freezestat trip. However, a freezestat
trip will de-energize the associated compressor. If the call for
cooling is still present at the end of the ASCD and the freezestat
has closed, the unit will resume operation.
Low Ambient Cooling (Smart Equipment™ Control)
To determine when to operate in low ambient mode, the UCB
has an Outdoor Air Temperature Sensor (OAT) with a low
ambient setpoint at 45ºF (default). When the OAT Sensor
senses a temperature below the low ambient setpoint and the
thermostat is calling for cooling, the UCB will operate in the low
ambient mode.
Low ambient mode operates the compressors in this manner:
10 minutes on, 5 minutes off. The indoor blower is operated
throughout the cycle. The 5-minute off period is necessary to
defrost the indoor coil.
Low ambient mode always begins with compressor operation.
Compressor minimum run time may extend the minutes of
compressor operation. The off cycle will begin immediately
following the elapse of the minimum run time.
When operating in low ambient mode, an Evaporator Low
Limit Sensor (EC1) temperature below 26ºF will de-energize
the compressor. If the call for cooling is still present at the end
of the ASCD and the evaporator temperature (EC1) is above
26ºF, the unit will resume operation.
Safety Controls
The unit control board monitors the following inputs for each
cooling system:
1. A suction line freezestat (Simplicity Lite Control) to protect
against low evaporator temperatures due to a low airflow or
a low return air temperature, (opens at 26 ± 5 °F and resets
at 38 ± 5°F) or an evaporator low limit sensor (EC1)
(Located on the Suction Line at the Evaporator Coil.)
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