Vertiv | Liebert PEX4 | User Manual
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General Maintenance
4.3. Control Component Appearance Inspection
Carry out visual inspection and simple function test by referring to the following items:
1. Visually inspect the power transformers and isolation transformers, and test the output voltage of the indoor
unit and the outdoor unit.
2. Check that there are no signs of aging on the control interface board, control board, temperature and
humidity sensor board and fuse board.
3. Clean the electrical control elements and control board of dust and dirt with a brush and electronic dust
removing agent.
4. Check and fasten the I/O ports at the control interface board, including the connection between control
board and control interface board, as well as between the temperature/humidity sensor board and the
interface board.
5. Check the connection between the user terminals (70#, 71#, 70A#, 71A#, 37#, 38#) and the control interface
board.
6. Check the output connection between the control interface board and various contactors and solenoid
valves for liquid pipes. Also check the input connection between control interface board and fan overload
protector, high pressure switch, heating over-temperature protection switch, humidifier protection switches,
discharge air temperature sensor, and a low pressure sensor. Check the connection parts such as high
pressure switches and solenoid valves, and replace the component if are in poor connection or faulty.
7. Check and replace electrical components that are faulty, such as control fuses (or MCBs) and control boards.
8.
Check the specification and aging condition of the control cable and power cable between the indoor unit
and the condenser, and replace the cables when necessary.
9. Use temperature and humidity measuring meters with higher precision to measure and calibrate the
temperature and humidity sensors.
• Set the humidity control mode to ‘relative humidity control’ during the calibration process.
•
Adjust the setpoints. Check the action of the functional parts and the auto-flush control logic of water pan
of the infrared humidifier according to the control logic.
• Simulate and check the operation of the protection devices including high and low pressure alarm, high
and low temperature alarm, high water level alarm and over-temperature protection.
• Check the water detection sensor.
