General Information; Infinity Controlled Low Ambient Cooling - Carrier Infinity 25VNA Installation Instructions Manual

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.
NOTE: Contactor may close intermittently without the unit
starting. This is done to determine whether the control needs to
energize the crankcase heater. Closing the contactor powers the
inverter and allows the system to check compressor temperature.
Outdoor Fan Motor Operation
The outdoor unit control (Fig. 11) energizes outdoor fan anytime
compressor is operating, except for defrost and as needed during
low- -ambient cooling operation. The outdoor fan remains
energized if a pressure switch opens or compressor scroll over
temperature should occur. This OD fan is an ECM motor which
operates at varying speeds depending on the ambient and the
demand.
Time Delays
The unit time delays include:
S Five minute time delay to start cooling or heating operation
when there is a call from the user interface. To bypass this
feature, momentarily short and release Forced Defrost pins.
S Five minute compressor re- -cycle delay on return from a
brown- -out condition.
S See Tab le 7 for other delay information.

General Information

Infinity Controlled low ambient cooling:

This unit is capable of low ambient cooling down to 0_F
(- -17.8_C) with Low Ambient enabled on the Infinity Control. A
low ambient kit is not required.
The Infinity Control provides an automatic evaporator coil freeze
protection algorithm that eliminates the need for an evaporator
freeze thermostat. The only accessory that may be required is wind
baffles in locations which are likely to experience cross winds in
excess of 5 miles an hour. This generally occurs only on roof and
open area applications.
Low ambient cooling must be enabled in the User Interface setup.
Fan may not begin to cycle until about 40_F (4.4_C) OAT. The
outdoor unit fan will cycle on and off based on outdoor coil
temperature, outdoor air temperature, and suction pressure
measurements to keep the compressor running at the proper
conditions.
Utility Interface With Infinity Control
The utility curtailment relay should be wired between the two
UTIL connections on the control board for this Infinity
Communicating System (see Fig. 20). This input allows a power
utility device to interrupt compressor operation during peak load
periods. When the utility sends a signal to shut the system down,
the User Interface will display, "Curtailment Active". See UI
installation instructions for setup details.
Communication and Status Function Lights
Infinity Control, Green Communications (COMM)Light
A green LED (COMM light) on the outdoor board (see Fig. 11)
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.
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.
S One minute time delay of outdoor fan at termination of cooling
mode when outdoor ambient is greater than or equal to 100_F
(37.8_C).
S Fifteen second delay at termination of defrost before the
auxiliary heat is de- -energized.
STATUS
LED
COMM
LED
Fig. 11 - - Variable Speed Control Board
Defrost
This user interface (UI) offers 5 possible defrost interval times: 30,
60, 90, 120 minutes, or AUTO. The default is AUTO.
Defrost interval times: 30, 60, 90, and 120 minutes or AUTO are
selected by the Infinity Control User Interface (dip switches are not
used.)
AUTO defrost adjusts the defrost interval time based on the last
defrost time as follows:
S When defrost time <3 minutes, the next defrost interval=120
minutes.
S When defrost time 3- -5 minutes, the next defrost interval=90
minutes.
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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