Control Functions And Sequence Of Operation - Carrier Infinity 24ANB6 Installation Instructions Manual

Disconnect factory provided wires from A, B, C, and D terminals.
Using factory provided wires, connect to C and Y on the control
board for 2 wire thermostat control. A field installed jumper wire
is also required between R and Y (See Fig. 14). Connect field 24V
wires to factory provided wires now connected to C and Y and cap
both sides or remove unused factory provided wires.
Compressor Internal Relief
The compressor is protected by an Internal Pressure Relief (IPR)
which relieves discharge gas into the compressor shell when
differential between suction and discharge pressure exceeds
550- -625 psi. The compressor is also protected by an internal
overload attached to motor windings.
GENERAL SEQUENCE OF OPERATION
STANDARD THERMOSTAT
Turn on power to indoor and outdoor units. Transformer is
energized.
On a call for cooling, thermostat makes circuits R- -Y and R- -G.
Circuit R- -Y energizes contactor, starting outdoor fan motor and
compressor circuit. R- -G energizes indoor unit blower relay,
starting indoor blower motor on high speed.
NOTE: To achieve the rated system performance, the indoor unit
or the thermostat must be equipped with a time delay relay circuit.
When thermostat is satisfied, its contacts open, de- -energizing
contactor and blower relay. Compressor and motors stop. If indoor
unit is equipped with a time- -delay relay circuit, the indoor blower
will run an additional 90 sec to increase system efficiency.
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_F (37.78_C).
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_F (37.78_C)
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_F (37.78_C).
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 for approximately 10 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_F
(37.78_C).
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. 9 - - Utility Interface
With Non- -Communicating Thermostats
When the utility curtailment interface is used
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 (12.78_C) to a
minimum of 0 _F (- -17.78 _C) 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
7
UTIL
*
A05410
with a