Troubleshooting guide

OM 931-3 / Page 17 of 28
Three-Speed Fan Operations
Table 7: Three-Speed Fan
Continuous Fan
Compressor On
Electric Heat
Space Temp Satised
Low Speed
Of
f
Of
f
Compressor
Of
f
Med. Speed
Of
f
Heating/Cooling
Electric Heat Enabled
Of
f Off
High Speed
Two-Speed Fan Operations
Table 8: Two-Speed Fan
Continuous Fan
Compressor On
Electric Heat
Space Temp Satised
Low Speed
Of
f
Of
f
Compressor
Of
f
High Speed
Of
f
Heating/Cooling
Electric Heat Enabled
Of
f Off
High Speed
Circuit Two, Additional Operating
Modes
The I/O Expansion Module controls the second circuit high
pressure, low pressure, and low suction line temperature
operating conditions in the same manner as the main board
controls the rst circuit.
Table 9: I/O Expansion Module LED & Fault Outputs
Status LED's
Thermostat Alarm
Mode / Fault
Yellow Green Red
Light Output
Terminal “A”
Invalid Conguration
Flash Flash Off De-energized
Jumper Setting
Base Board
Off Flash Flash N/A
Communication Fail
High Pressure #2 Fault Off Off Flash De-energized
Low Pressure #2 Fault Off Off On De-energized
Low Suction Temp #2 Fault Flash Off Off De-energized
Sensor Failures Low Suction
Low Suction Temp #2, Flash Flash On De-energized
1
EWT (w/ Boilerless EH only)
2
Service Test Mode Enabled Flash Flash Flash De-energized
Unoccupied Mode On On Off Energized
Occupied, Bypass,
Standby, or Tenant
Off On Off Energized
Override Modes
Note: Mode / Faults are listed in order of priority.
1
Boilerless electric heat only
2
Alarm/fault LED indications take precedence over
service test mode LED indication. The controller shall
use service test mode if the service test mode jumper
is installed, even if the LED’s indicate an alarm/fault.
Operation
Dual Circuit Units
• Provides standard lead / lag operation for two compressors
in dual circuit units
• Circuit one will come on rst when there is any call for
heating or cooling at the main board
• The second circuit will be enabled after the interstage
timer has expired. The interstage timer defaults to 300
seconds
• HP, LP, SLTS fault for either circuit one or circuit two,
will lockout the entire unit and subject for intelligent reset
Thermostat Inputs (Y2, W2)
• The Y2 terminal which is cooling mode stage two,
energizes the second compressor
• If Y1 and Y2 thermostat inputs are active at the same time,
interstage timers will be used to stage the compressor up
and down
• The W2 terminal which is heating mode stage two,
energizes the second reversing valve followed 30 seconds
later by the second compressor
• If W1 and W2 thermostat inputs are active at the
same time, interstage timers will be used to stage the
compressors up and down
Electric Heat Controls
Boilerless Heat Coil Control
• Turns on the factory installed heater when the entering
water temperature is less than 55°F, the temperature set
point is not adjustable
• For geothermal applications the factory installed electric
heater turns on when the entering water temperature is less
than 30°F
Note: In both cases the compressor is shut down.
Multiple Speed Fan Control
• When the Water Source Heat Pump is equipped with an
I/O Expansion Module and factory installed electric heat,
three speed fan control is possible.
• If the thermostat is calling for continuous fan operation
and the compressor is not running the fan motor will run
in low speed.
• If there is a call for heating or cooling (compressor is
running) the fan motor will run in medium speed.
• If the electric heater is enabled the fan motor does not run
in high speed.
Note: On units with an I/O Expansion Module and no electric
heat, it is possible to congure the I/O Expansion
Module for a two speed fan. If there is a call for
continuous fan (compressor off) the fan motor runs
in low speed. If there is a call for heating or cooling
(compressor on) the fan motor runs at high speed.