Ope ra ti onmode
1→ 2→ 3→ 4→5→6→7→8 VALVE CLOSE
8→ 7→ 6→ 5→4→3→2→1 VALVE OPEN
ON
1
ON
2
OFF
3
OFF
4 5
OFF OFF
6
OFF
7
ON
OFF ON ON ON OFF OFF OFF OFF
OFF OFF OFF ON ON ON OFF OFF
OFF OFF OFF OFF OFF ON ON ON
8
④
③
②
①
④
③
②
①
Con ne ct or
Pin N o.
12V
0.9V
50ms. 75ms .
200ms.
6-6. Electric expansion valve control circuit
Fig. 6-14
Main P.W.B.
Electric
expansion
valve
Microcomputer
Valve4
Valve3
Valve2
Valve1
●
Electric expansion valve is driven by B-12V. Opening of the valve is controlled by feeding power to 1
or 2 phases of the 4-phase coil to switch the polarity of the coil.
●
The relation between the conducting phase switching direction and open/close direction is as shown
below. When the power is turned on, approx. 0.9 V is applied to CN15 pins 1 to 4 ; when no power
is supplied, approx. 12 V is applied. When the power is reset, expansion valve performs initial
operation for 5 to 10 seconds.During initial operation, measure pins 1 to 4 of CN15 using
multimeter: If no change is found around 0.9 V or 12V
, expansion valve or microcomputer is
defective.
●
Fig. 6-15 shows logic waveform during the operation of expansion valve.
Table 6-4
Fig. 6-15
CN 15
Pin No.
Lead
wire
Drive status
White
Yellow
Orange
Blue
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