Service Manual

44
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).
S Fifteen second delay at termination of defrost before the
auxiliary heat (W2) is de- energized.
S Twenty second delay at termination of defrost before the
outdoor fan is energized.
S Seventy and sixty second compressor delays when Quiet
Shift- 2 enabled.
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 between R & Y.
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 Non- communicating thermostat
S Low Ambient Pressure Switch Kit
S Evaporator Freeze Thermostat
S Hard Start kit
S Crankcase Heater
S Field Supplied Isolation Relay
Support feet are recommended for low ambient cooling. See
Product Specification sheet for kit part numbers on
appropriate unit size and series unit.
DEFROST
This control offers 4 possible defrost interval times: 30, 60,
90 or 120 minutes. They are selected by dip switches on the
control board, or in the Observer Communicating Wall
Control (if used). The Observer Communicating Wall Control
selection overrides the control board dip switch settings.
Auto defrost is available with Observer Communicating Wall
Control only and it must be enabled in the Wall Control. Auto
defrost adjusts the defrost interval time based on the last
defrost time as follows:
S When defrost time is < 3 minutes, the next defrost interval
= 120 minutes
S When defrost time is 3- 5 minutes, the next defrost interval
= 90 minutes
S When defrost time is 5- 7 minutes, the next defrost interval
= 60 minutes
S When defrost time is > 7 minutes, the next defrost interval
= 30 minutes
Fig. 32 – Heat Pump Single Stage Control Board