MCAC-VTSM-2014-04 R410A DC Inverter V4 Plus 50Hz
Troubleshooting 99
5.4 E4: Pipe temperature T3/Ambient temperature sensor (T4) error (Display on faulty unit, all the
ODU in standby)
Case: There is no display on main board of one system, and the problem still exists after replacing main
board. Voltage values on measuring plate (such as 220V, 5V, 12V, etc.) are normal; after measuring
resistance value of sensor, find that T4 thermo-bulb is earth-continuity, and further discover that the
thermal cable of T4 sensor is punched by bolt, as follows:
Note:
1. How to check whether the compressor is short circuit
①
:
The normal resistance value of inverter compressor among U V W is 0.7~1.5Ω, and infinity to earth. If the resistance value is
out of the range, the compressor is abnormal.
2. How to check whether the fan motor is short circuit
②
:
The normal value of DC fan motor coil among U V W is less than 10Ω, and the value of AC fan motor coil is from a few ohm to
hundreds of ohm for different fan motor model. If the measured value is 0Ω, the fan motor is short circuit.
3. How to check whether the inverter module is output error
③
:
Let PN and UVW of inverter module short circuit, then dial multimeter to buzzer file, if the multimeter is ring, the inverter
module is output error.
E4: Pipe temperature T3/Ambient temperature
sensor (T4) error
T3/T4 port on main
board is loose
T3/T4 sensor is short circuit or
disabled (Using a multimeter to
measure resistance, if the resistance is
too small, the sensor is short circuit, if
the resistance in certain temperature is
not consistent with attached table 1,
the sensor is disabled)
MC9S08AC128chip is disabled
T4 sensor is worn out and
connected with sheet metal
After being reconnected, the
system becomes normal
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