Service Manual

42
For standard refrigerant line lengths (80 ft/24.38 m or less),
allow system to operate in cooling mode at least 15 minutes.
If conditions are favorable, check system charge by
subcooling method. If any adjustment is necessary, adjust
charge slowly and allow system to operate for 15 minutes to
stabilize before declaring a properly charged system.
If the indoor temperature is above 80_F /26.67_C, and the
outdoor temperature is in the favorable range, adjust system
charge by weight based on line length and allow the indoor
temperature to drop to 80_F/26.67_C before attempting to
check system charge by subcooling method as described
above.
If the indoor temperature is below 70_F / 21.11_C, or the
outdoor temperature is not in the favorable range, adjust
charge for line set length above or below 15ft (4.57 m) only.
Charge level should then be appropriate for the system to
achieve rated capacity. The charge level could then be
checked at another time when the both indoor and outdoor
temperatures are in a more favorable range.
NOTE: If line length is beyond 80 ft (24.38 m) or greater
than 20 ft (6.10 m) vertical separation, See Long Line
Guideline for special charging requirements.
SINGLE- STAGE AC (*SA5, *SA6)
GENERAL SEQUENCE OF OPERATION -
STANDARD THERMOSTAT
Turn on power to indoor and outdoor units. Transformer is
energized.
On a call for cooling, thermostat makes circuits R- Y and
R- G. 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.
NOTE: To achieve the rated system performance, the indoor
unit or the thermostat must be equipped with a time delay
relay circuit.
When thermostat is satisfied, its contacts open,
de- energizing contactor and blower relay. Compressor and
motors stop. If indoor unit is equipped with a time- delay
relay circuit, the indoor blower will run an additional 90 sec
to increase system efficiency.
AC CONTROL 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 Operation
This product utilizes either a standard indoor thermostat or
Observer Communicating Wall Control. With a call for
cooling, the outdoor fan and compressor are energized.
When the cooling demand is satisfied, the compressor and
fan will shut off.
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).
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 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_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- communicating thermostat, the utility relay should be
wired in series with the Y input.
Low Ambient Cooling
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 require the installation of
accessory kits:
S Low Ambient Pressure Switch Kit
S Evaporator Freeze Thermostat
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.