Toshiba e-STUDIO4500c Service Manual page 774

PHOTOCONDUCTOR UNITS (PCU)
The temperature/humidity sensor at the black PCU detects the relative humidity
inside the machine.
When the relative humidity stays at 60% for 10 minutes:
1) The Peltier unit turns ON.
2) The Peltier circulation fan and PCU fans turn on together and run at half-
speed.
3) The Peltier cooling fan turns on and runs at full speed.
The operation changes when the relative humidity goes below 50% for 5 minutes:
1) The Peltier unit turns OFF.
2) The Peltier circulation fan turns OFF.
When the humidity stays below 50% for another 5 minutes:
1) The Peltier cooling fan turns OFF.
2) The PCU fans turn OFF.
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August, 2006