Installation guide
INST ALLATION INSTRUCTIONS R- 410A Split System Air Conditioner
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Communication and Status Function Lights
Green Communications (COMM) Light (Communicating
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 1 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 c rankcase 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 communicating wall
control.
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 communicating 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 Non- Communicating Thermostats
Utility curtailment will only work when the unit is operating
with a non- communicating thermostat.
When the utility curtailment interface is applied with a
non- c ommunicating thermostat, the utility relay should be
wired in series with the Y input.
Low Ambient Cooling
With Non- Communicating Thermostats
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 applications requ ire the installation of
accessory kits:
S Low Ambient Pressure Switch Kit
S Evaporator Freeze Thermostat
S Winter Start Control
S Hard Start kit
S Crankcase Heater
Support feet are recommended for low ambient cooling. See
Product Specification sheet for kit part numbers on
appropriate unit size and series unit.
For low ambient cooling with the Observer
Communicating Wall Control the cooling lockout must be
set to “Off” in the Wall Control setup.
Liquid Line Solenoid
When operating in communicating mode the standard
thermostat terminals will not function. A terminal on the
non- communicating thermostat bus labeled “LS” on the AC
control board is provided for wiring liquid line solenoids when
in communicating mode. For operation in communicating
mode wire solenoid valve kit NASA401LS across LS and C
terminals . For operation in non - communicating mode wire
solenoid valve kit NASA401LS across C and Y terminals.
If the thermal cutout trips for three consecutive cycles, then
unit operation is locked out for 4 hours and the appropriate
fault code (See Table 1) is displayed.
CONTACTOR SHORTED DETECTION
If there is compressor voltage sensed when there is no
demand for compressor operation, the contactor may be
stuck closed. The control will flash the appropriate fault
code. Check the contactor and control box wiring.
NO 230V AT COMPRESSOR
If the compressor voltage is not sensed when the
compressor should be starting, the contactor may be stuck
open or the unit disconnect or circuit breaker may be open.
The control will flash the appropriate fault code. Check the
contactor, unit disconnect or circuit breaker and control box
wiring.
TEMPERATURE THERMISTORS
Thermistors are electronic devices which sense temperature.
As the temperature increases, the resistance decreases.
Thermistors are used to sense outdoor air (OAT) and coil
temperature (OCT).
If the outdoor air or c oil thermistor should fail, the control will
flash the appropriate fault c ode. (See table 1).
IMPORTANT: The outdoor air thermistor and coil thermistor
are factory mounted in the correct locations. Do not re- locate
thermistor sensors.
THERMISTOR SENSOR COMPARISON
The control continuously monitors and compares the outdoor
air temperature sensor and outdoor coil temperature sensor
to ensure proper operating conditions. The comparison is, if
the outdoor air sensor indicates 10_F( - 12.22_C) warmer
than the coil sensor (or) the outdoor air sensor indicates
20_F( -6.67_C) cooler than the coil sensor, the sensors
are out of range.
If the sensors are out of range, the c ontrol will flash the
appropriate fault code. (See Table 1).
FAILED THERMISTOR DEFAULT OPERATION
Factory defaults have been provided in the event of failure of
outdoor air thermistor and/or coil thermistor.
Thermistor Curve: The resistance vs. temperature chart
shown in Figure 18 enables the technician to check the
outdoor air and outdoor coil thermistors for proper resistance.
Unplug the thermistor assembly from the circuit board and
measure resistance across each thermistor. For example, if
the outdoor temperature is 60_F (15.56_C), the resistance
reading across the outdoor air thermistor should be around
16,000 Ohms.