Carrier 50XCA06-24 User Manual
30
Operating sequence
All units require the addition of a thermostat accessory
package to complete the control circuit. The sequence of
operation may vary depending on which package is
selected.
Room-mounted thermostat — The unit uses an
electronic thermostat mounted in the conditioned space.
Fan circulation — When the thermostat selector switch is
set to the FAN position, the evaporator-fan motor will
operate to provide air circulation.
Cooling — The evaporator will operate continuously or
when the compressor runs, depending on the setting of the
thermostat fan selector switch. When the thermostat closes
(on a call for cooling), the control relay condenser-fan con-
tactor and compressor contactor(s) close. The control relay
will start the indoor fan if it is not already running. The
condenser fan contactor will start the condenser air fan
and the compressor contactors will immediately start the
compressor(s).
package to complete the control circuit. The sequence of
operation may vary depending on which package is
selected.
Room-mounted thermostat — The unit uses an
electronic thermostat mounted in the conditioned space.
Fan circulation — When the thermostat selector switch is
set to the FAN position, the evaporator-fan motor will
operate to provide air circulation.
Cooling — The evaporator will operate continuously or
when the compressor runs, depending on the setting of the
thermostat fan selector switch. When the thermostat closes
(on a call for cooling), the control relay condenser-fan con-
tactor and compressor contactor(s) close. The control relay
will start the indoor fan if it is not already running. The
condenser fan contactor will start the condenser air fan
and the compressor contactors will immediately start the
compressor(s).
A second stage on 50XCA12 to 24 units will close if
additional cooling demand is required, and will start the
second-stage compressor. When the thermostat is satisfied,
the second-stage compressor will stop first, and then the
first-stage compressors will stop when cooling demand is
satisfied. The condenser will also stop as soon as both cool-
ing stages are satisfied.
second-stage compressor. When the thermostat is satisfied,
the second-stage compressor will stop first, and then the
first-stage compressors will stop when cooling demand is
satisfied. The condenser will also stop as soon as both cool-
ing stages are satisfied.
A 5-minute timer, TDR (time-delay relay), will prevent
the compressor(s) from restarting for 5 minutes after any
compressor has stopped.
All units — The control circuit incorporates a current
sensing lockout relay (Cycle-LOC™ device) that locks off
the compressor(s) when any safety device is activated (low
or high pressure switches, or compressor internal over-
load). If any compressor safety device opens, the compres-
sor will stop. High and low-pressure switches and
compressor motor overload protectors will reset automati-
cally when the condition which caused the device to trip
has dropped below the reset condition. To reset the Cycle-
LOC control device, manually turn the control power OFF,
then back ON.
compressor has stopped.
All units — The control circuit incorporates a current
sensing lockout relay (Cycle-LOC™ device) that locks off
the compressor(s) when any safety device is activated (low
or high pressure switches, or compressor internal over-
load). If any compressor safety device opens, the compres-
sor will stop. High and low-pressure switches and
compressor motor overload protectors will reset automati-
cally when the condition which caused the device to trip
has dropped below the reset condition. To reset the Cycle-
LOC control device, manually turn the control power OFF,
then back ON.
Controls