Mitsubishi Electric PUH-P8YE Technical & Service Manual page 28

(5) Bypass solenoid valve control (SV1)
1) Control at cooling
1 While the compressor is stopped, the solenoid valve is OFF.
2 When the power is turned on, or when the compressor is restarted after it has been stopped for 30 minutes or
longer, if the liquid temperature (TH1) in 25 °C or higher then the solenoid valve turns ON for 2 minutes.
3 When the mode is changed from heating to cooling, solenoid valve operation conforms to item 2.
2) Control at heating
1 While the compressor is stopped, the solenoid valve is OFF.
2 When the power is turned on, or the compressor is restarted after it has been stopped for 30 minutes or longer,
the solenoid valve turns ON for 2 minutes.
3 When the mode is changed from cooling to heating, the solenoid valve turns ON for 2 minutes at starting.
4 When the control pressure switch (63H2) trips, the solenoid valve turns ON.
5 If 63H2 resets 15 minutes after tripping, the solenoid valve turns OFF.
6 During defrosting, the solenoid valve turns ON.
(6) Electronic expansion valve (LEV)
1) Initial processing after power turned on
After the power is turned on, full close processing is performed as initial drive processing.
a A 2200 pulses down is output from power on.
b At the end of 2200 pulse down output, 60 pulses up is output.
c Sixty pulses up output ends initial processing. At this point, the valves are fully closed.
2) Control contents
At compressor starting
At compressor stopping
At defrosting
Normal
3) Normal LEV control
1 The operation frequency when the compressor is started (including after defrosting reset) determines the stan-
dard opening angle.
2 After 1 above, sub cool (SC) shown below controls the LEV opening angle.
<Definition of SC>
Cooling: SC = TH3 (outdoor unit)-TH1 (outdoor unit)
Heating: SC = TH5 (indoor unit)-TH2 (indoor unit)
* When there are multiple indoor units, the value of TH2 and TH5 is the average value of TH2 and TH5 of all
the indoor units.
<LEV control>
LEV is controlled so that SC is equal to SCm.
SC < SCm:
SC > SCm:
SC = SCm:
SCm = 5~15 (SCm is different with Indoor Units.)
4) Transient LEV control
1 When outlet temperature (outdoor unit TH2) rises
When the outlet temperature (outdoor unit TH2) exceeds 115 °C, the LEV opening angle is made larger.
(7) Service functions
1) Abnormality history clear
1 When DIP SW1-2 is turned ON while the compressor is operating or stopped, the abnormality history is cleared.
LEV output opening angle
Initial opening angle
1000 pulses
2000 pulses (full close)
See next item
LEV opening angle is made smaller
LEV opening angle is made larger
LEV opening angle remains unchanged
Opening angle control range
Approx. 1000 to 2000 pulses
–
–
1000 to 1500 pulses
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