Control Functions And Sequence Of Operation - Carrier Performance 24APA Installation Instructions Manual

CONTROL FUNCTIONS
AND SEQUENCE OF OPERATION
The outdoor unit control system has special functions. The
following is an overview of the control functions.
SEQUENCE OF OPERATION
Cooling Operation
This product utilizes either a standard indoor thermostat or
Infinity communication User Interface. With a call for cooling,
the outdoor fan and compressor are energized. When the cooling
demand is satisfied, the compressor and fan will shut off.
NOTE: The outdoor fan motor will continue to operate for one
minute after compressor shuts off, when the outdoor ambient is
greater than or equal to 100 degrees F.
Communication and Status Function Lights
Green Communications (COMM) Light (Infinity Control
only):
A green LED (COMM light) on the outdoor board indicates
successful communication with the other system products. The
green LED will remain OFF until communications is established.
Once a valid command is received, the green LED will turn ON
continuously. If no communication is received within 2 minutes,
the LED will be turned OFF until the next valid communication.
Amber Status Light
An amber colored STATUS light is used to display the operation
mode and fault codes as specified in the troubleshooting section.
See Table 3 for codes and definitions.
NOTE: Only one fault code will be displayed on the outdoor
unit control board (the most recent, with the highest priority).
Crankcase Heater Operation
The crankcase heater (when applicable) is energized during the
off cycle below 65 degrees F.
Outdoor Fan motor Operation
The outdoor unit control energizes outdoor fan any time the
compressor is operating. The outdoor fan remains energized for
15 minutes if a pressure switch or compressor thermal protector
should open. Outdoor fan motor will continue to operate for one
minute after the compressor shuts off when the outdoor ambient
is greater than or equal to 100 degrees F.
Time Delays
The unit time delays include:
S Five minute time delay to start cooling operation when
there is a call from the thermostat or user interface (there
is no bypass of this feature in a non- -communicating
system, in a communicating system push the UI fan and
up buttons simultaneously
seconds)
S When operating the unit with 2 wires, this delay is
shortened to 10 seconds.
S Five minute compressor recycle delay on return from a
brown out condition
S Two minute time delay to return to standby operation
from last valid communications (with Infinity only)
S One minute time delay of outdoor fan at termination of
cooling mode when outdoor ambient is greater than or
equal to 100 deg F
for approximately 10
Utility Interface
With Infinity Control
The input labeled UTIL is active only when a communicating
Infinity Control is used. This input allows a power utility device
to interrupt compressor operation during peak load periods. See
figure below for wiring connections. When the utility sends a
signal to shut the system down, the User Interface will display
"CURTAILMENT ACTIVE".
INFINITY BOARD
R
UTILITY RELAY
UTILITY SIGNAL
OPEN RELAY
*
SUPPLIED BY UTILITY PROVIDER
Fig. 11 --- Utility Interface
With Non- -Communicating Thermostats
W h e n t h e u t i l i t y c u r t a i l m e n t i n t e r f a c e i s u s e d w i t h a
non- -communicating thermostat, the utility relay should be wired
in series with the Y input.
Low Ambient Cooling
When this unit is required to operate below 55_F to a minimum
of 0_F outdoor temperature, provisions must be made for low
ambient operation.
Low ambient cooling operation can be accomplished two ways
depending on the control system:
S Complete Infinity System
S Standard non- -communicating thermostat
Infinity Controlled low ambient cooling:
This unit is capable of low ambient cooling without a kit ONLY
when using a complete Infinity system. A low ambient kit is not
required, and the outdoor fan motor does not need to be replaced
for Infinity controlled low ambient operation. The Infinity
Control provides an automatic evaporator coil freeze protection
algorithm that eliminates the the need for an evaporator freeze
thermostat. Low ambient cooling must be enabled in the User
Interface set up. Fan may not begin to cycle until about 40_F
OAT. Fan will cycle based on coil and outdoor air temperature.
A crankcase heater must be installed. See Product Data for
accessory part numbers on appropriate unit size and series.
Infinity controlled low ambient mode operates as follows:
S Fan is OFF when outdoor coil temp is < (outdoor air
temperature + 3 _F) or outdoor fan has been ON for 30
minutes. (Fan is turned off to allow refrigerant system to
stabilize.)
S Fan is ON when outdoor coil temp > (outdoor air
temperature + 25_F) or outdoor coil temp > 80_F or if
outdoor fan has been OFF for 30 minutes. (Fan is turned
on to allow refrigerant system to stabilize.)
S Low pressure switch is ignored for first 3 minutes during
low ambient start up. After 3 minutes, if LPS trips, then
outdoor fan motor is turned off for 10 minutes, with the
compressor running. If LPS closes within 10 minutes
then cooling continues with the outdoor fan cycling per
10
UTIL
*
A05410