Operation; Cooling Sequence Of Operation - York International ZQ Series Installation Manual

Operation

Compressor Operation
Compressor Operation details include:
1. Compressors are controlled by the Y1 through
Y2 thermostat inputs. If the Lead/Lag function
is turned OFF, a Y1 input energizes the C1
output when the compressor number 1 anti-
short cycle delay is at 0 and all refrigerant
safety devices are closed (Default 5 minutes).
2. The FAN output for indoor fan operation
energizes with any cooling output after the
Indoor Fan Cool On Delay expires.
3. When the thermostat cooling inputs are
lost and the minimum runtime expires, the
compressor outputs stage off (Default 3
minutes).
4. A 30 second interstage delay occurs when
multiple stages are requested.
Note: A Y2 input without a Y1 input
energizes a C1 first and then C2 30
seconds later.

Cooling sequence of operation

The factory Unit Control Board (UCB) refers to either
the Everyday Thermostat Control (ETC) board, or the
Smart Equipment™ control board. Both the ETC and
the Smart Equipment™ control boards operate in
similar fashion, and are described below. When a
difference in operation between the ETC and Smart
Equipment™ board exists, a description of both
operations will be described.
With a demand for first stage cooling either from a
thermostat or space sensor, the low-voltage control
circuit to "C1" and "G" is completed. For first stage
cooling, the compressor is energized and the 1st
stage operates. The UCB will energize the VFD
equipped blower motor at low speed as set in the
Smart Equipment™ control. When the thermostat
calls for the second stage of cooling, the low-voltage
control circuit to "C2" is completed. The control
board energizes the 2nd stage of the compressor.
If there is an initial call for both stages of cooling,
the UCB will delay energizing the 2nd stage of the
compressor by 30 seconds in order to avoid a power
rush. Once the thermostat has been satisfied, it
will de- energize C1 and C2. If the compressor has
satisfied the minimum run time (3 min. default), the
compressors and condenser fans are de-energized.
Otherwise, the unit operates until the minimum
run has been completed. Upon the compressor
62 INSTALLATION MANUAL ZQ SERIES 3 - 5 ton 60 Hertz R-410A
de-energizing, the blower is stopped following the
elapse of the fan off delay for cooling.
The call is passed to the Unit Control Board (UCB),
which then determines whether the requested
operation is available and, if so, which components
to energize.
If at any time a call for both heating and cooling are
present, the heating operation will be performed.
If operating, the cooling system is halted as with
a completion of a call for cooling. Heating always
takes priority.
Continuous Blower
By setting the room thermostat fan switch to "ON,"
the supply air blower will operate continuously.
Intermittent Blower
With the room thermostat fan switch set to "AUTO"
and the system switch set to either the "AUTO" or
"HEAT" settings, the blower is energized whenever
a cooling or heating operation is requested. The
blower is energized after any specified delay
associated with the operation.
When energized, the indoor blower has a minimum
run time of 30 seconds. Additionally, the indoor
blower has a minimum off delay of 10 seconds.
No Outdoor Air Options
When the thermostat calls for cooling, the low-
voltage control circuit from "R" to "Y1" and "G"
is completed. The compressor and condenser fan
motor are energized. After completing the specified
fan on delay for cooling, the UCB will energize the
blower motor.
Once the thermostat has been satisfied, it will de-
energize Y1. If the compressor has satisfied its
minimum run time, the compressor and condenser
fan de-energize. Otherwise, the unit operates the
cooling system until the minimum run time for
the compressor has been completed. After the
compressor de-energizes, the blower is stopped
following the elapse of the fan off delay for cooling.
To be available on the ETC and Smart Equipment™
controller, a compressor must not be locked-out
due to a high or low-pressure switch or freezestat
trip. Additionally on the Smart Equipment™
controller, the Evaporator Low Limit sensor (EC1)
detecting a temperature below 26°F and the anti-
short cycle delay (ASCD) must have elapsed.
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