Tadiran Telecom Swift Inverter 9U, Service Manual

Page: 44 / 115

43
(5) E4- Internal fan error of wall mounted air conditioner (DC motor)
Explanation of
error
Cause: The internal fan of some highly energy efficient models is DC
motor using a green plug through which the main internal control panel
can drive the motor and sense the current rotational speed feedback.
When the main internal control panel cannot receive the rotational
speed feedback signal of the motor, it will indicate “DC motor error”.
Disappearance of the rotational speed feedback signal may be caused
by:
1 The motor is stuck and cannot work; 2 The speed feedback element
inside the fan is destroyed; 3 There’s something wrong with the speed
feedback signal receiving circuit of the main internal control panel.
Inspection path: Is DC motor stuck by foreign matter→motor
destroyed → Motor terminal connectors→Main internal control panel
Tools required
for inspection
Multimeter, a DC motor in normal working condition
Frequent
problematic part
Mechanical jam of internal fan, internal DC motor, main internal
control panel
Inspection
procedure and
key points
1. Check whether the fan accelerates to extremely high speed before
the error occurs. If it can work for a period, the reason of mechanical
jam can be excluded.
2. Plug and unplug the terminal of the DC motor again to exclude any
fan error due to connector loosening, and pull the terminal slightly for
inspection if necessary.
3. Replace the motor in the faulted air conditioner with other DC motor
to plug in the main internal control panel (do not fix it with the fan for
the time being), if the main control panel still indicates “DC motor
error”, then replace the main internal control panel; if the error
disappears, replace the DC motor.
4. Multimeter can be used to distinguish whether it is main control
panel problem or motor problem by: connect the motor with the main
control panel and pay attention to the second (yellow) and fourth
(black) wire from the outermost side among four lines of the terminal
of the DC motor. After the air conditioner powers on in the cooling
mode for a while, the voltage between the yellow and black wires
should rise gradually and the motor should accelerates slowly, if the
DC motor still won’t rotate, then the DC motor is destroyed.
Special attention
Five lead wires division: Count from the outermost side of the four
wires of the DC motor terminal, the first blue wire is the speed
feedback wire with a voltage of 0.5-5V when the fan rotates; the
second yellow wire is the motor driving wire with a voltage of
2.0-7.5V when the fan rotates; the second white wire is 15V power
cord with a voltage of 15V in normal condition; the fourth black wire
is 0V DC earth wire which is the benchmark of all the voltage tests; the
fifth (red) wire is 310V wire which is strong with a voltage of 310V in
normal condition, so be careful of electric shock.