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6. Press ENTER key to scroll to the Fan Overrides?
7. Press UP or DOWN keys to change the value from
No to Go. The override will begin and the screen
will change to the override screen (see Figure 34).
The override will last for 5 minutes or until the Fan
Overrides parameter is set to No again.
Liquid Pressure Sensor
The unit has a pressure transducer installed on the liquid
line between the condenser and electronic expansion
valve (EEV). The transducer is used for condenser fan
speed control and for monitoring of system operation.
The liquid line transducer is also referred to as the
discharge or liquid pressure sensor.
The discharge/liquid pressure sensor input can be
verified and adjusted by:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
TECHNICIAN password 1313.
3. Press UP or DOWN keys to scroll to I/O Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Analog Inputs;
press ENTER key.
5. Press UP or DOWN keys to scroll to Analog Ins C3-7
(for circuit 1) or Analog Ins C3-9 (for circuit 2).
6. Verify the measurement displayed on screen is
accurate (see Figure 35).
7. If the measurement needs to be adjusted, apply an
offset value by pressing the ENTER key to scroll to
Offset.
8. Press UP or DOWN keys to adjust the offset. The
update will not take effect until the cursor is
moved out of the offset parameter.
9. Once adjusted, the ESCAPE key several times to
return to Main Menu screen.
FIGURE 35
Adjusting Discharge/Liquid Transducer
Pressure Values
Manual 2100-749
Page
24 of 68
Troubleshooting the Discharge/Liquid Pressure
Transducer
0-650 psig
.5 to 4.5v
4.5-.5 + 4 volt range/650 psig = .00615 volts per 1 psig
Example: 325 psig x .00615 + .5 v = 2.5 volts
Formula for Tech:
Measured Pressure x .00615 + Voltage Offset =
Expected Transducer Signal Voltage (see Figure 36).
FIGURE 36
Voltage to Pressure:
Discharge/Liquid Pressure Transducer
Voltage Offset
Discharge/Liquid Pressure Transducer Alarm
When the discharge pressure sensor value is out of
range (0-650 PSIG), the controller will generate a
sensor failure alarm to indicate the sensor is not
working properly.
This alarm is fixed and cannot be adjusted.
Liquid Temperature Sensor
The unit is equipped with a liquid line temperature
sensor to monitor the temperature of the liquid
refrigerant leaving the condenser and entering the EEV.
The temperature is measured with a 10k ohm NTC
thermistor.
The liquid temperature sensor can be verified and
adjusted by:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
TECHNICIAN password 1313.
3. Press UP or DOWN keys to scroll to I/O Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Analog Inputs;
press ENTER key.
5. Press UP or DOWN keys to scroll to Analog Ins C3-
13 (for circuit 1) or Analog Ins C3-15 (for circuit
2).
6. Reference the Value to verify the temperature (see
Figure 37).
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Troubleshooting
