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Hot Gas Bypass (Optional)
This option allows the system to operate at lower loads without
excessive on/off compressor cycling. The hot gas bypass
option is required to be on both refrigerant circuits because of
the lead / lag feature of the controller.
This option allows passage of discharge gas into the
evaporator inlet (between the TX valve and the evaporator)
which generates a false load to supplement the actual chilled
water or air handler load.
NOTE: The hot gas bypass valve should not generate a
100% false load.
The pressure regulating valve is factory set to begin opening
at 110 psig with R-410a and can be changed by adjusting the
pressure setting. To raise the pressure setting, remove the
cap on the bulb and turn the adjustment screw clockwise. To
lower the setting, turn the screw counterclockwise. Do not
force the adjustment beyond the range it is designed for as
this will damage the adjustment assembly. The regulating
valve opening point can be determined by slowly reducing
the system load while observing the suction pressure. When
the bypass valve starts to open, the refrigerant line on the
evaporator side of the valve will begin to feel warm to the
touch.
A solenoid valve is located ahead of the bypass valve and is
controlled by the MicroTech
first stage of cooling on a circuit is active.
The hot gas line may become hot enough to cause injury. Be
careful during valve checkout.
VFD Low Ambient Control
(Optional)
The optional VFD fan control is used for unit operation below
32°F (0°C) down to a minimum of -10°F (-23.3°C). The control
looks at the saturated discharge temperature and varies
(pressure) at the "target" temperature. This temperature is
established as an input to a setpoint screen labeled "Sat
Condenser Temp Target."
Compressor Communications
The CoreSense™ compressor communication module
on model sizes 070-240 provides advanced diagnostics,
protection, and communications that enhance compressor
performance and reliability.
Features include motor temperature protection, scroll
temperature protection, missing phase protection, reverse
phase protection, low control circuit voltage protection, short
cycling detection and alert, operational and fault history
storage, and LED status display.
IOM 1206-7 • TRAILBLAZER
III controller. It is active when the
®
WARNING
MODEL AGZ CHILLERS
™
Warnings and Alerts
A solid green LED indicates the module is powered and
operation is normal.
A solid red LED indicates an internal problem with the module.
A flashing green LED communicates Warning codes. Warning
codes do not result in a trip or lockout condition.
A flashing red LED communicates Alert codes. Alert codes will
result in a trip condition and possibly a lockout condition
Warning Codes (Flashing Green LED )
Code 1 – Loss of Communication: The module will flash the
green Warning LED one time indicating the module has not
communicated with the master controller for longer than 5
minutes.
Code 2 – Reserved For Future Use
Code 3 – Short Cycling: The module will flash the green
Warning LED three times indicating the compressor has short
cycled more than 48 times in 24 hours.
Code 4 – Open/Shorted Scroll Thermistor: The module will
flash the green Warning LED four times indicating an open/
shorted
Alert/Lockout Codes (Flashing Red LED)
Code 1 – Motor High Temperature: The module will flash the
red Alert LED one time indicating the motor is onerheating .
A code 1 Alert will open the M2-M1 contacts. The Alert will
reset after 30 minutes. Five consecutive Code 1 Alerts will
lockout the compressor. Once the module has locked out the
compressor, a power cycle or Modbus reset command will be
required for the lockout to be cleared.
Code 2 – Open/Shorted Motor Thermistor: The module will
flash the red Alert LED two times indicating the motor PTC
thermistor circuit has an open/shorted thermistor chain (see
Table 2). A Code 2 Alert will open the M2-M1 contacts. The
Alert will reset after 30 minutes and the M2-M1 contacts will
close if the resistance of the motor PTC circuit is back in the
normal range. The module will lockout the compressor and a
power cycle or Modbus reset command will be required to clear
the lockout.
Code 3 – Short Cycling: The module will flash the red Alert
LED three times indicating the compressor is locked out due to
short cycling. Once locked out the compressor, a power cycle
or Modbus reset command will be required to clear the lockout.
Code 4 – Scroll High Temperature: The module will flash
the red Alert LED four times indicating the over-temperature
condition. A Code 4 Alert will open the M2-M1 contacts.The
Alert will reset after 30 minutes. Once the module has locked
out the compressor, a power cycle or Modbus reset command
will be required to clear the lockout.
Code 5 – Reserved for Future Use
Code 6 – Missing Phase: The module will flash the red Alert
LED six times indicating a missing phase. The Alert will reset
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