Hitachi RAM-60QH4 Manuel De Service page 114

• Pulse output from pin
75
When command value is input, FAN-HIC performs disconnection detection operation for fan motor and then supplies
current to fix fan at specified position. While switching power supplying phases, gradually fan speed then increases to
the specified rotation speed.
• At this time, it will take about 40 to 60 seconds for fan speed to reach specified value.
Relationship between command voltage
and rotation speed is shown in Fig. 13-4
1000
( min
−1 ）
0
1V
Fig. 13-4
• If only the outdoor fan cannot be operated, perform checking in the following manner.
Check to see that 2A fuse is not blown.
Turn the power off.
(1) Disconnect the connector of fan motor and measure resistance of motor coil: Resistance between each terminal is
about 120 Ω normally.
(2) Measure resistance between each terminal of P.W.B. connector CN24 and black lead side of R917: If short-
circuited, driver 2 is defective.
(3) Measure resistance between each terminal of P.W.B. connector CN24 and cathode side of D906: If short-circuited,
driver 1 is defective.
(4) Measure resistance between both terminals of R917. Resistance is about 2Ω normally: If short-circuited or about
200 Ω or more, it is defective.
• Connect the connector, turn the power on and perform operation using Service switch.
(1) Is command voltage input to pin
If specified voltage is not output from pin
(2) Is fan locked by some object?
As defective parts, driver 1, driver 2, R917, D904-D906 can be considered.
of microcomputer is smoothed by C901 and input to FAN-HIC.
Command
( V )
voltage
5V
of FAN-HIC?
13
of microcomputer, microcomputer is defective.
75
Command voltage of RAM-60QH4 is shown in Table 13-1.
(Voltage at pin of FAN-HIC)
13
Table 13-1
Step Heating
HiHi 4.27
Hi 4.12
Lo 3.73
S 3.73
– 126 –
Cooling
4.27
3.73
3.73
3.73