Mitsubishi Electric MFZ-KJ25VE Service Manual page 14

9-4. HEAT ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF)(MFZ-KJ25/35/50VE)/ STOP/OPERATE (OFF/ON)(MFZ-KJ25/35/50VE2) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select HEAT mode with OPERATION SELECT button.
(3) Press TEMPERATURE buttons TEMP
1. Cold air prevention control
When the compressor is not operating or is starting, and the temperature of indoor heat exchanger and/or the room tem-
perature is low or when defrosting is being done, the indoor fan will stop or rotate in Very Low speed.
2. High pressure protection
The compressor operational frequency is controlled by the temperature of the indoor heat exchanger to prevent the con-
densing pressure from increasing excessively.
When the temperature of indoor heat exchanger becomes too high, the high pressure protection works.
This mode continues until the temperature of indoor heat exchanger falls.
3. Defrosting
Defrosting starts when the temperature of outdoor heat exchanger becomes too low.
The compressor stops once, the indoor/outdoor fans stop, the 4-way valve reverses, and the compressor re-starts.
This mode continues until the temperature of outdoor heat exchanger rises or the fixed time passes.
9-5. 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 minuets have passed with the room temperature 2 degrees below the
set temperature.
HEAT mode changes to COOL mode when 15 minuets have passed with the room temperature 2 degrees 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. (MFZ-KJ25/35VE-
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 ↔ HEAT) and becomes a state
of standby. (MFZ-KJ25/35VE-
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.
9-6. 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 V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing VANE CONTROL (
OBH666C
or button to select the desired temperature. The setting range is 16 - 31°C.
,
E2 ER2
, , MFZ-KJ25/35VE2-
E2 ER2
(AUTO) (1) (2)
, MFZ-KJ25/35VE2- ,
E1 ER1
, , MFZ-KJ50VE/VE2)
E1 ER1
(3) (4)
14
, MFZ-KJ50VE/VE2)
) button.
(SWING)