Operating Sequence; Typical Installation - Carrier 50ZPA Product Data

Operating sequence

Cooling Operation (024 - 042)
With a call for cooling (Y/Y2), the indoor fan energizes imme-
diately where as the contactor energizes after a 5 minute time
delay (in case of an initial start up) starting the compressor and
the outdoor fan motor. When the cooling demand is met, Y/Y2
de-energizes, shutting the compressor, indoor fan and the out-
door fan.
Cooling Operation (048 and 060)
These units utilize a 2 stage indoor thermostat. With a first stage
call for cooling (Y1), the indoor fan (low stage) energizes im-
mediately where as the contactor energizes after a 5 minute time
delay (in case of an initial start up) starting the compressor (low
stage) and the outdoor fan motor. If the low stage operation can-
not satisfy the cooling demand, the second stage cooling (Y2)
energizes switching the compressor into high stage cooling
through energizing an internal solenoid valve inside the scroll
compressor and switching the indoor fan into high stage. When
second stage cooling is satisfied, Y2 de-energizes switching the
compressor and the indoor fan into low stage cooling. When the
low stage cooling demand is met, Y1 de-energizes shutting the
compressor, indoor fan and the outdoor fan.

Typical Installation

16
RETURN
AIR
TOP COVER
Power Wiring
Control Wiring
Condenser Airflow
*Separate disconnect per NEC
(National Electrical Code) required
for electric heater when single-
Evaporator Airflow
point conection is not used.
Heating Operation (024 - 042)
With a call for heating (W2), the auxiliary or electric heat ener-
gizes along with the indoor blower. In case of staged heating,
W3 is energized if the demand is not met. The highest airflow
selected is run while the electric heat is in operation. When heat-
ing demand is met, W3 and W2 sequentially de-energize shut-
ting the indoor fan and the electric heater.
Heating Operation (048 and 060)
With a call for heating (W2), the auxiliary electric heater is en-
ergized along with the indoor blower. If the demand is not met,
W3 is energized in case of staged heating. When heating de-
mand is satisfied, W3 and W2 sequentially de-energize along
with the indoor fan blower.
Continuous Fan:
With the continuous indoor fan option selected on the thermo-
stat, G is continuously energized. In case of 024 - 042 units, the
selected airflow setting is provided. In case of 048 and 060
units, the system runs low stage (Y1) airflow for continuous fan
operation.
INDOOR
THERMOSTAT
POWER AND
LOW-VOLTAGE
ENTRY
COMPOSITE
RUST-PROOF
BASEPAN
CONDENSATE
DRAIN
CONNECTION
FROM
POWER
SOURCE
DISCONNECT
PER NEC*
(UNIT AND
ELECTRIC
HEATER)
C00008