A/A DC INVERTER U-MATCH AIR CONDITIONERS MAINTENANCE
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Temperature sensor: measure the grounding resistance between the points 3.3V and IPM15V (the testing
method is same as above); if the grounding is shortcut, please check if each temperature sensor is damaged or if
there is arcing trace on its outer housing or metal ends
Reactor: if the communication error remains after the replacement of the electric control box, then pull out the
two terminals of the reactor and measure the resistance between them with a universal meter; if the measure valve
is about several ohms, it indicates the terminals of the reactor is likely to break off.
Fan motor: pull out the terminals of the fan motor and measure the resistance between the red, brown and black
wires with a universal meter; The normal value is about several hundreds ohms, if the measure value is beyond this
range, it indicates there is a open circuit or the fan motor is defective.
Compressor: apart from the badly running environment, improper connection, or systematic abnormity, if H5 still
occurs frequently after the replacement of the electric control box, then it indicates that the compressor is probably
defective.
Four-way valve: pull out two purple wires and measure the resistance between them with a universal meter to
see if it is about 1~2K. If it is much larger, it indicates that there is a open circuit among the coils of the four-way
valve which then should be replaced.
If the fault is beyond the statement above, then please check the indoor unit.
2 .After the Replacement of the Electric Control Box of the Indoor Unit
If the fault remains after the replacement of the electrical control box of the indoor unit, then there is a need to
check if the wiring is proper and the fan motor and temperature sensor is in good condition. Besides, if the fault is
beyond the statement above, please check the outdoor unit.
2.2.4 Precautions
1. Prior to the replacement of the main board of the outdoor unit’s control box, it must be certain that it is the qualified
product and necessary tests as follows should be taken:
a, test if there is a short circuit between any two of three IGBI pins. If so, the main board can not be used.
b. test if there is a short circuit between the points P and N of the DC bus. If so, the main board can not be used.
c. test if there is a short circuit between any U/V/W and P, U/V/W and N. If so, the main board can not be used.
d. see the section 1.2.3 for the test point and testing method of IGBT and IPM module.
2. Each compressor is matched with only certain type main board of the electric control box, so prior to the
replacement of the main board, it must be sure what model the main board is; otherwise the main board would fail to
match with the compressor.
3 .As for the replacement of the compressor, it also must be sure what model the compressor is ( it can be found on
the label of the fan motor capacitor); otherwise the compress would failed to match with the piping system and the
electric control box.
4. Never allow any wire to contact the pipes, four-way valve, compressor, and sharp edge of the metal sheet. And
the earth leads of the compressor, fan motor and electric control box must be inside a separate screw hole.
5. Necessary measurers should be taken to against water, moisture and static electricity. Besides, during the
dismantlement and installation of the electrical control box, a antistatic strip must be put on and do not touch the
component as much as possible.
6.The wiring should be done strictly according to the wiring diagram labeled on the electric control box and each
wiring terminal should be on the right place. Besides the wires can not be stretched too tightly or else it would break
away from the socket, connector or the insulating bushing. The bonding tie should be kept 3mm～5mm long, as the
longer one would cause unusual sound by the friction with the cover plate.
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