Power Transistor Check - Daikin FT25CV1A Service Manual

Si01-406
5.10

Power Transistor Check

Check No.13
Note: Check to make sure that the voltage between the terminal of Power transistor (+) and (-) is
approx. 0 volt before checking power transistor.
< Measuring method >
Disconnect the compressor harness connector from the outdoor unit PCB. To disengage the
connector, press the protrusion on the connector.
Then, follow the procedure below to measure resistance between power transistor (+) and (-)
and the U, V and W terminals of the compressor connector with a multi-tester. Evaluate the
measurement results for a pass/fail judgment.
<Power transistor check>
Negative (-) terminal of
tester (positive terminal
(+) for digital tester)
Positive (+) terminal of
tester (negative terminal
(-) for digital tester)
Normal resistance
Unacceptable resistance
<Measuring positions>
MULTIMETER
(DC, VOLTAGA RANGE)
Service Diagnosis
Power transistor
(+)
UVW
DB1
TRM1
S90 THERMISTOR LEAD WIRE
COMPRESSOR LEAD WIRE
UVW Power transistor
(-)
Power transistor UVW
(+)
Several kΩ to several MΩ (∗)
Short (0 Ω) or open
S80 FOUR WAY VALVE LEAD WIRE (Heating Pump only)
S70 FAN MOTOR LEAD WIRE
REACTOR LEAD WIRE
Check
UVW
Power transistor
(-)
(R2956)
121