Snowfall Fan Control : Tcb-Pcmo4Ul; External Master On/Off Control : Tcb-Pcmo4Ul - Carrier MMY-MAP0724FT9UL Service Manual

7-3-3. Snowfall Fan Control : TCB-PCMO4UL

SW1: Snowfall detection switch (snowfall sensor)
Operation
An external snowfall signal turns on the outdoor unit fan.
Terminal
COOL
(SW1)
The input signal is recognized during its rising/falling phase.
(After reaching the top/bottom of the rising/falling edge, the signal must remain there for at least 100 ms.)
The optional P.C. board should be connected to the header outdoor unit (U1).

7-3-4. External master ON/OFF Control : TCB-PCMO4UL

SW1: Operation input switch
SW2: Stop input switch
Operation
The system is started/stopped from the outdoor unit.
Terminal
COOL
(SW1)
HEAT
(SW2)
The input signal is recognized during its falling phase. (After reaching the bottom of the falling edge, the signal
must remain there for at least 100 ms.)
CAUTION
(1) Do not turn on the COOL (SW1) and HEAT (SW2) terminals simultaneously.
(2) Be sure to provide a contact for each terminal.
External signal: No-voltage pulse contact
The optional P.C. board should be connected to the header outdoor unit (U1).
Header outdoor unit
Connection
Outdoor unit
cable
interface PCB
CN509
Input signal Operation
Snowfall fan control
ON
(Turns on outdoor
OFF
unit fan)
Normal operation
ON
(Cancels control)
OFF
Header outdoor unit
Connection
Outdoor unit
cable
interface PCB
CN512
Input signal Operation
Turns on all indoor
ON
units
OFF
Turns off all indoor
ON
units
OFF
Locally procured
Optional PCB
TB1
COM
COOL
PJ17
HEAT
Shield
wire
Locally procured
Optional PCB
TB1
COM
PJ17 COOL
HEAT
Shield
wire
– 73 –
Snowfall sensor
SW1
SW1
SW2