Gree Ultra Heat GMV Multi VRF Heat Recovery Series Service Manual page 154

Ultra Heat GMV VRF Technical Service Manual_Heat Recovery Serial
2) Set a multimeter to gear diode.
For Drive board:
Use the black probe of the multi-meter to touch the place marked by P and the red probe to touch
places marked by U, V and W respectively and record readings of the multi-meter. Use the red probe to
touch the place marked by N and black probe to touch places marked by U, V and W respectively and
record readings of the multi-meter.
For PFC board:
Use the black probe of the multi-meter to touch the place marked by P and the red probe to touch
places marked by L1, L2 and L3 respectively and record readings of the multi-meter. Use the red probe
to touch the place marked by N and black probe to touch places marked by L1, L2 and L3 respectively
and record readings of the multi-meter.
3) Analyzing: If the reading ranges between 0.3 V and 0.7 V in the above-mentioned six scenarios,
the IPM module is normal. If the reading is 0 in one or multiple scenarios, the IPM module is damaged.
2.1.2 Precondition: units cannot be normally started
Step 1: Disconnect the power supply of the units and open the electric junction box of the
compressor to see whether wiring of the compressor is intact.
Step 2: Measure the resistance between two wiring terminals (U, V, W). The resistance value range
should be 0.5~2.0 Ω.
Measure the resistance to earth of each wiring terminal. The value should be 10 MΩ. If not, the
compressor has an internal fault.
Step 3: Check the solenoid valves of the system, include electric expansion valves, oil return valves,
and oil balance valves. Refer to the preceding section for the test method.
Step 4: Check the IPM module. Refer to the preceding section for the test method
2.2 Compressor Replacement
Step 1: Disconnect power supply.
Turn off the power switch of the ODUs and disconnect the line of the power supply and the power
line of the ODUs. Meanwhile, cover the power line with tape for insulation and put a warning sign beside
the power switch to prevent electric shock.
Step 2: Clear electric parts (do not need to disassemble the electric box).
Before removing compressors' lines, temperature sensors, and electric heaters, mark them so that
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