2-9. EXPANSION VALVE CONTROL (LEV CONTROL)
(1) Outline of LEV control
The LEV basic control is comprised of setting LEV opening degree to the standard opening degrees set for each opera- tional frequency of the compressor. However, when any change in indoor/outdoor temperatures or other factors cause air conditioning load fluctuation, the LEV control also works to correct LEV opening degree based on discharge temper- ature (Shell temperature) of the compressor, developing the unit’s performance.
standard | specification |
general operation
Control range | from minimum 33 | |
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Actuating speed | LEV opens 40 pulse/second and close 90 pulse/second | |
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Opening degree adjustment | LEV opening degree is always adjusted in opening direction. | |
| (When reducing the opening degree, LEV is once over- | |
| closed, and then adjusted to the proper degree by opening. | |
Unit OFF | LEV remains at maximum opening degree (reaches maxi- | |
| mum opening degree approximate in 15 minutes after com- | |
| pressor stops) | |
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Remote controller ON | LEV is positioned. (first | |
| positioned.) | |
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COOL · DRY MODE | LEV is fixed to standard opening degree according to opera- | |
During 1 to 5 minutes after compressor starts | tional frequency of compressor. | |
HEAT MODE (MUZ) |
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During 1 to 15 minutes after compressor starts |
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More than COOL, DRY: 5/ HEAT: 15 (MUZ) minutes | LEV opening degree is corrected to get target discharge | |
have passed since compressor | temperature of compressor. | |
| (For discharge temperature lower than target temperature, | |
| LEV is corrected in closing direction.) | |
| (For discharge temperature higher than target temperature, | |
| LEV is corrected in opening direction.) | |
| wIt may take more than 30 minutes to reach target tempera- | |
| ture, depending on operating conditions. | |
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Thermostat OFF | LEV is adjusted to exclusive opening degree for thermostat | |
| OFF. | |
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Thermostat ON | LEV is controlled in the same way as that after the compres- | |
| sor has started up. |
Defrosting in HEAT mode (MUZ)
LEV is adjusted to open 500 pulse.
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