Manual 2100-670B
Page
20 of 33
Troubleshooting the Discharge/Liquid Pressure
Transducer
0-650 psig
0-5v
4v/650 psig = .00615 volts per 1 psig
Example:
325 psig x .00615 + .5 v = 2.5 volts
Formula for Tech:
Measured Pressure x .00615 + Sensor Offset =
Expected Transducer Signal Voltage (see Figure 26).
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.
Alarm index numbers: 153, 154, 155, 156
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
Disch Temp
Sensor (C3)
; press ENTER key.
5. Reference the
Value
to verify the temperature (see
Figure 27).
6. If an offset needs to be applied, press ENTER key
to scroll to
Offset
.
7. Press UP or DOWN keys to change the offset to
desired value.
8. Press ENTER key to save.
9. Press ESCAPE key several times to return to Main
Menu screen.
Condenser Fan Operation
Condenser Fan Speed Control
The condenser fan motor maintains its high efficiency
across a wide operating range. The result is a
significant reduction in energy use when the motor is
run at reduced speeds (see Table 8).
FIGURE 27
Adjusting Discharge/Liquid Temperature Input
Mode
Speed %
Controller
Output Volts
CFM
HR36AP*
High
Ambient
58 – 100
5.8 v –
10.0 v
2430 –
2660
Low
Ambient
25 – 58
2.5 v –
5.8 v
1085 –
2430
Normal
58
5.8 v
2430
HR58AP*
High
Ambient
71 – 100
7.1 v –
8.0 v
2726 –
3060
Low
Ambient
25 – 71
2.5 v –
7.1 v
1130 –
2726
Normal
71
7.1 v
2726
TABLE 8
Condenser Fan Speeds
High Pressure Control
Condenser Fan Speed
When the liquid pressure reaches 590 PSI, the
condenser fan will begin to speed up to attempt to
bring the pressure back down. The speed will continue
to ramp up until the liquid pressure reaches 630 PSI.
FIGURE 26
Voltage to Pressure:
Discharge/Liquid Pressure Transducer
