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Carrier Yileng - Shanghai, China
8.3 - High-pressure safety switch
30XQ units are equipped with high-pressure safety switches. In accordance with the applicable code the high-pressure
switches with manual reset, called PZH (former DBK), may be backed up by high-pressure switches that require
resetting with a tool. The high-pressure switches that require resetting with a tool are called PZHH (former SDBK). If a
PZHH cuts out, the corresponding PZH in the same compressor is faulty and must be replaced. The PZHH must be reset
with a blunt tool with a diameter of less than 6 mm. Insert this tool into the opening on the pressure switch and push the
reset button in this location. These pressure switches are located at the discharge of each compressor.
8.4 - Air side exchanger
The 30XQ coils are with internally grooved copper tubes with aluminum fins are available
8.5 - Fan
The fan is axial Flying Bird fans equipped with rotating shroud and made of composite recyclable material. Each motor
is fixed with transverse supports. The motors are three-phase, with permanently lubricated bearings and insulation class
F.
8.6 - Electronic expansion valve (EXV)
The EXV is equipped with a stepper motor (2785 to 3690 steps, depending on the model) that is controlled via the EXV
board. The EXV is also equipped with a sight glass that permits verification of the mechanism movement and he
presence of the liquid gasket.
8.7 - Moisture indicator
Located on the EXV, permits control of the unit charge and indicates moisture in the circuit. The presence of bubbles in
the sight-glass indicates an insufficient charge or non-condensable in the system. The presence of moisture changes the
color of the indicator paper in the sight-glass.
8.8 - Filter drier
The role of the filter drier is to keep the circuit clean and moisture-free. The moisture indicator shows, when it is
necessary to change the element. A difference in temperature between the filter inlet and outlet shows that the element is
dirty.
The filter should be replaced at least once per year.
8.9 - Sensors
The units use thermistors to measure the temperature, and pressure transducers to control and regulate system operation
(see 30XQ - Pro-Dialog Control IOM for a more detailed explanation).
8.10 - 4-way valve
4-way valve is used to realize change over automatically between cooling mode and heating mode. In fact, 4-way valve
mostly acted during changeover of heating mode and defrost mode. The minimum pressure differential is 350kPa to
drive valve changeover.
NOTE: To decrease valve failure risk, when valve changeover is necessary at first running test or weather seasons
interchange, it is not allowed to changeover operation mode until the maintenance and service persons ensure the
valve should keep present mode operating at least 10 minutes.
Unit change operation mode from cooling mode to heating mode, first need operate 10 minutes at cooling mode, then
stop unit, select heating mode and start again. The process is same as the changeover from heating mode to cooling
mode.
Warning: to ensure valve reliable work, it will be better keep power on when unit is stopped, especially operates at
cooling mode and defrost mode. If it has to cut off power to examine and repair, please check and verify the
