Fan Orientation Control Box End - York YD480 Series Installation Manual

voltage. Refer to the wiring labels inside of the unit
control access panel for additional information.
Continuous Blower
By setting the room thermostat to "ON," the low voltage control
circuit from the "R" to "G" is completed and 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 in cooling mode, the indoor blower has a
minimum run time of 30 seconds. Additionally, the indoor
blower has a delay of 10 seconds between operations.
Cooling Sequence Of Operation
When the thermostat calls for the first stage of cooling, the low-
voltage control circuit from the "R" to "Y1" (UCB 1 Y1) and "G"
is completed and the first stage of cooling by energizing the M1
contactor of Compressor 1 and the RY1 (Outdoor Fan Relay)
for both condenser fans FM1 & FM2 of System 1. When the
LPS of UCB-1 falls below its cut-out point the CN-Fan output
brings on the PR1 and 1LLS (Solenoid) allowing refrigerant in
system 1 to flow for normal mechanical cooling function. After
completing the specified fan on delay for cooling, the UCB 1 will
energize FR1 (Indoor Fan Relay) energizing the indoor blower
motor via G1 output.
When the thermostat calls for the second stage of cooling, the
low-voltage control circuit from "R" to "Y2" (UCB 1 Y2) is
completed. The UCB 1 energizes the M2 contactor of
Compressor 2 and the RY2 (Staging Relay) for the 2LLS
(Solenoid) and both condenser fans FM1 & FM2 of System 1.
FM2 is controlled by pressure.
If there is an initial call for both stages of cooling, the SE control
board (UCB 1) will delay energizing compressor two by 30
seconds in order to avoid an excessive power rush.
When the thermostat calls for the third stage of cooling, the low-
voltage control circuit from the "R" replicate Y1 sequence into
Y2 as above to "Y3" (UCB 2 Y1) is completed. The SE control
board (UCB 2) activates the pump-out on start-up function and
the third stage of cooling by energizing the M3 contactor of
Compressor 3 and the RY3 (Outdoor Fan Relay) for both
condenser fans FM3 & FM4 of System 2. When the LPS of
UCB-2 falls below its cut-out point the PR2 relay brings on the
3LLS (Solenoid) allowing refrigerant in system 2 to return flow
to the compressor for normal mechanical cooling function. FR2
relay will also energize providing a G2 output as needed in
some applications.
When the thermostat calls for the fourth stage of cooling, the
low-voltage control circuit from "R" to "Y4" (UCB 2 Y2) is
completed. The UCB 2 energizes the M4 contactor of
Johnson Controls Unitary Products
Compressor 4 and the RY4 (Staging Relay) for 4LLS (Solenoid)
and both condenser fans FM3 & FM4 of System 2.
Once the thermostat has been satisfied, the SE control boards
will de-energize Y1, Y2, Y3 and Y4. If the compressors have
satisfied their minimum run times, the compressors and
condenser fans are de-energized. Otherwise, the unit operates
each cooling stage until the ASCD has elapsed. Upon the
completion of first stage cooling, the blower is stopped following
the completion of the fan off delay cycle.
Condenser Fan Operation
These condensing units are factory equipped with fan cycling
switches (PS1 System1 and PS2 System 2) to regulate system
head pressure. When outdoor ambient conditions are cool, the
head pressure of any air conditioning system may drop too low
for optimal performance. These condensing units maximize
system performance in a variety of ambient conditions by
incorporating fan cycling switches to maintain proper system
head pressure.
On these condensing units, the condenser fans of a given
system (1 or 2) are powered when a compressor call is made
(C1, C2 (UCB1) C1, C2 (UCB2)) & the respective compressor
is energized. Fan FM1 (System 1) or Fan FM3 (System 2) will
start immediately upon a call for first or third stage cooling.
Figure 11: Fan Orientation Control Box End
However, Fan FM2 (System 1) or Fan FM4 (System 2) is
equipped with a fan cycling switch (PS1 or PS2) and will not
start until the system head pressure reaches 480 psig. Fan 2 or
4 will operate until the system head pressure drops below 300
psig where the fan cycling switch will shut the fan down. The
unit will continue to operate Fan FM1 or FM3 until the system
head pressure again reaches 480 psig at which time Fan FM2
or FM4 will restart. Condenser fans operate as above
regardless of lead-lag preference.
Operation With A Four-Stage Thermostat
If the total system is to be controlled with a 4-stage thermostat:
1. Terminals Y1 and Y2 of the Smart Equipment™ control
board (UCB 1) controlling System 1, should be connected
to stages 1 and 2 of the 4-stage thermostat.
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