Carrier Infinity 25VNA8 Installation Instructions Manual page 10

Crankcase Heater Operation
This unit has an internal crankcase heater that will be energized
during the off cycle and is intelligently demanded by the system to
prevent the compressor from being the coldest part of the system
thus enhancing the reliability. The crankcase heater will function
as needed any time the outdoor unit is powered. The indoor unit
and UI do not need to be installed for the crankcase heater to
operate properly.
The compressor windings will occasionally be energized during
the OFF cycle (depending on the length of the OFF cycle) to start
the stator heat operation, thus maintaining a sump temperature that
is essential for compressor reliability. The compressor will not run
during this process.
Outdoor Fan Motor Operation
The outdoor unit control (Fig. 12) energizes outdoor fan anytime
the compressor is operating, except for defrost. The OD fan motor
is variable speed. The speed will change depending on the ambient
temperature and the cooling or heating capacity required.
Time Delays
The unit time delays include:
S 3.5 minute time delay after last cycle, initial power up, return
from brown- -out condition. To bypass this feature, momentarily
short and release Forced Defrost pins.
S At the end of every compressor ON cycle, there will be 150
seconds of PEV open period for pressure equalization followed
by 15 seconds of PEV Off period before the next compressor
ON cycle. This delay cannot be bypassed as it helps compressor
reliability.
S 15 second delay at termination of defrost before the auxiliary
heat is de- -energized.
S See Table 7 for other delay information.
Fig. 12 - - AOC Control Board
Communication and Status Function Lights
Infinity Touch Control, Green Communications
(COMM)Light
A green LED (COMM light) on the outdoor board (see Fig. 12)
indicates successful communication with the other system
products. The green LED will remain OFF until communication 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. The green LED will be turned off when using a
standard 2- -stage non- -communicating heat pump thermostat.
Amber Status Light
Amber colored STATUS light indicates operation and error status.
See Table 7 for definitions.
S Two minute time delay to return to standby operation from last
valid communication.
Defrost
This user interface (UI) offers 5 possible defrost interval times: 30,
60 and 90 minutes, or AUTO. The default is AUTO.
Defrost interval times: 30, 60, and 90 minutes or AUTO are
selected by the Infinity Touch Control User Interface if using UI.
The 90 and 120 minute selection will default to 60 minutes at
ambient below 37 degrees. The 120 minute selection will default
to 90 minutes at ambient above 37 degrees.
If using non- -communicating thermostat, defrost intervals are set
using dip switches on outdoor control board (see Fig. 12). AUTO
defrosts adjusts the defrost interval time based on the last defrost
time as follows:
S When defrost time <5 minutes, the next defrost interval=90
minutes. (outdoor temperature above 37_F)
S When defrost time 5- -7 minutes, the next defrost interval=60
minutes.
S When defrost time >7 minutes, the next defrost interval=30
minutes.
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