Midea MCD-18HRFN1-QRC4 Service Manual page 114

Electrical Control Function
1.3.9 Drain pump control (For Duct & Cassette)
Adopt the water-level switch to control the action of drain pump.
Main action under different condition :( every 5 seconds the system will check the water level one time)
1. When the A/C operates with cooling (including auto cooling) and forced cooling mode, the pump will start
running immediately and continuously, till stop cooling.
2. Once the water level increase and up to the control point, LED will alarm and the drain pump open and
continue checking the water level. If the water level fall down and LED disalarmed (drain pump delay close 1
minute) and operate with the last mode. Otherwise the entire system stop operating ( including the pump)
and LED remain alarming after 3 minutes.
1.3.10 Follow me
1) If the indoor PCB receives the signal which results from pressing the FOLLOW ME button on remote
controller, the buzzer will emit a sound and this indicates the follow me function is initiated. But when the
indoor PCB receives signal which sent from remote controller every 3 minutes, the buzzer will not
respond. When the unit is running with follow-me function, the PCB will control the unit according to the
temperature from follow-me signal, and the temperature collection function of room temperature sensor
will be shielded.
2) When the follow-me function is available, the PCB will not respond according to the setting temperature
from follow-me signal every 3 minutes.
3) The PCB will take action to the mode change information from remote controller signal, and the
follow-me function will be turned off. (if the wired remote controller does not initiate follow me function).
4) When the unit is running with follow-me function, if the PCB doesn't receive any signal from remote
controller for 7 minutes or pressing FOLLOW ME button again, the follow-me function will be turned off
automatically, and the temperature collection function of room temperature sensor will be available, the
PCB will control the unit according to the room temperature detected from its own room temperature
sensor and setting temperature.
When the indoor PCB receives the follow-me signal from wired remote controller, the control is the
5)
same as that from wireless remote controller, but buzzer will not respond. When the PCB receives
turning-off follow-me signal from wired remote controller, the unit will quit follow-me function at once.
The follow-me function controlled by wired remote controller prevails that by wireless remote controller.
1.3.11 Point Check Function(18-36K)
There is a check switch in outdoor PCB.
Press the switch SW1 to check the states of unit when the unit is running.
Press the switch N times it will display the content corresponding to No. N. After getting into the check
function, it will display No. N with 1.5s, meanwhile the low bit decimal of digit display flashing, indicated to
get into the check function display. After 1.5s, it will display the content corresponding to No. N.
the digital display tube will display the follow procedure when push SW1 each time.
120 Electrical Control System