Mitsubishi Electric MUFZ-KJ-NAHZ Series Service Manual page 14

8-5. AUTO CHANGE OVER ··· AUTO MODE OPERATION
Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.
1. Mode selection
(1) Initial mode
At first indoor unit operates only indoor fan with outdoor unit OFF for 3 minutes to detect present room temperature.
Following the conditions below, operation mode is selected.
If the room temperature thermistor RT11 reads more than set temperature, COOL mode is selected.
If the room temperature thermistor RT11 reads set temperature or less, HEAT mode is selected.
(2) Mode change
In case of the following conditions the operation mode is changed.
COOL mode changes to HEAT mode when 15 minutes have passed with the room temperature 4 °F (2 degrees C)
below the set temperature.
HEAT mode changes to COOL mode when 15 minutes have passed with the room temperature 4 °F (2 degrees C)
below the set temperature.
In the other cases than the above conditions, the present operation mode is continued.
NOTE 1: Mode selection is performed when multi standby (refer to NOTE 2) is released and the unit starts operation
with ON-timer.
NOTE 2: If 2 or more indoor units are operating in multi system, there might be a case that the indoor unit, which is
operating in AUTO ( ), cannot change over the other operating mode (COOL
of standby.
NOTE 3: At the beginning of AUTO mode, the air flow direction and the fan speed are set to AUTO and the air outlet
selection is set to 2 FLOW.
8-6. AUTO VANE OPERATION
1. Horizontal vane (Horizontal vane/Multi-flow vane)
(1) Vane motor drive
These models are equipped with a stepping motors for the horizontal vanes. The rotating direction, speed, and angle
of the motor are controlled by pulse signals (approximately 12 VDC) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL (
(3) Positioning
The vane presses the vane stopper once to confirm the standard position and then moves to the set angle.
Confirming of standard position is performed in case of follows.
(a) The power supply turns on.
(b) The operation starts or finishes (including timer operation).
(c) The test run starts.
(d) The multi-standby starts or finishes.
(e) Every time the vane has swung more than the specified numbers of times.
( f ) The horizontal vane automatically moves in certain intervals to determine its position, and then it returns to
set position.
(g) The vane operates for the dew prevention.
(4) Air outlet selection
The air outlet(s) can be selected by pressing to VANE CONTROL (
When 2 FLOW is selected, air blows from the top and the front of the unit. When 1 FLOW is selected, air blows only
from the top of the unit.
(AUTO) (1) (2)
(2 FLOW)
(3) (4) (SWING)
) button.
(1 FLOW)
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HEAT) and becomes a state
) button.