General Sequence Of Operation - Carrier Infinity 25HNB5 Installation Instructions Manual

GENERAL SEQUENCE OF OPERATION

STANDARD THERMOSTAT
Turn on power to indoor and outdoor units. Transformer is
energized with power supplied.
Cooling
On a call for cooling, a standard thermostat (non–communicating)
makes circuits R–O and R–Y and R–G. Circuit R–O energizes
reversing valve, switching it to cooling position. 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.
When a standard thermostat (non–communicating) is satisfied, its
contacts open, de–energizing contactor and blower relay.
Compressor and motors should stop.
NOTE: If indoor unit is equipped with a time–delay relay circuit,
the indoor blower will run an additional 90 seconds to increase system
efficiency.
Heating
On a call for heating a standard thermostat (non–communicating)
makes circuits R–Y and R–G. Circuit R–Y energizes contactor,
starting outdoor fan motor and compressor. Circuit R–G energizes
indoor blower relay, starting blower motor on high speed.
Should temperature continue to fall, R–W2 is made through
second–stage room thermostat. Circuit R–W2 energizes a relay,
bringing on first bank of supplemental electric heat and providing
electrical potential to second heater relay (if used). If outdoor
temperature falls below setting of outdoor thermostat (factory
installed), contacts close to complete circuit and bring on second
bank of supplemental electric heat.
When thermostat is satisfied, its contacts open, de–energizing
contactor and relay. All heaters and motors should stop after all fan
off delays.
HEAT PUMP SYSTEM FUNCTIONS
AND SEQUENCE OF OPERATION
The outdoor unit control system has special functions.
following is an overview of the control functions.
SEQUENCE OF OPERATION
Cooling & Heating Operation
This product utilizes either a standard indoor thermostat or Infinity
communication User Interface. With a call for cooling, the outdoor
fan, reversing valve, and compressor are energized. When the
cooling demand is satisfied, the compressor and fan will shut off.
The reversing valve will remain energized until the control board
power is removed or a call for heating is initiated.
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.
With a call for heating, the outdoor fan and compressor are
energized. The reversing valve is de–energized in the heating
mode.
Communication and Status Function Lights
Green Communications (COMM) Light
(Infinity Control only)
A green LED (COMM light) on the outdoor board (see Fig. 13)
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.
Outdoor Air Temp (OAT)
Fig. 13 --- Control Board
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 4 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/18.33_C.
Outdoor Fan Motor Operation
The outdoor unit control energizes outdoor fan any time the
compressor is operating (except defrost and intermittently during
low ambient cooling). The outdoor fan remains energized for 15
The
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 or heating opera-
tion when there is a call from the thermostat or user inter-
face (To bypass this feature in a non–communicating
system, momentarily short and release forced defrost
pins, in a communicating system push the UI fan and up
buttons simultaneously for approximately 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 communication (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.
S Fifteen second delay at termination of defrost before the
auxiliary heat (W2) is de–energized
S Twenty second delay at termination of defrost before the
outdoor fan is energized
S Seventy and sixty second compressor delays when Quiet
Shift–2 enabled
9
Outdoor Coil Temp (OCT)
A05332