General Sequence Of Operation; Operation - Carrier 25HPA Performance Series Installation Instructions Manual

GENERAL SEQUENCE OF OPERATION

STANDARD THERMOSTAT
Turn on power to indoor and outdoor units. Transformer is
energized with power supplied.
Cooling
O n a c a l l f o r c o o l i n g , a s t a n d a r d t h e r m o s t a t
(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. The
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 deg F.
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. 14)
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 deg F.
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
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 deg F.
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