Mars Comfort-Aire Century VCD-SA Series Service Manual page 83

Service Manual - VCDxxSA
3.2 The fault warning
Alarm output:
An alarm output(CN33) can be utilized if actions are
required when a fault is present. This is a passive outlet
port, so you will need to input a voltage signal. The relay
is normally-open for normal operation, and closed when a
fault condition is active.
ALARM
3.3 Humidification control wiring
• To connect a humidifier, utilize the passive signal
"WORK" output (CN23) port as well as the G and C
wires on the controller, and wire the humidistat and
humidifier per above wiring diagram. When the fan
is running, the CN23 relay will be closed, which will
allow power to the humidifier when the humidistat
is below humidity setpoint. If the thermostat or
zone controller has an HUM interface, connect the
humidifier directly to the HUM and C ports.
WORK
24V control signal or 208/230V power supply
HUMIDISTAT
G
24-VAC
C
3.4 Dehumidification control wiring
S4
DH
ON
1 2
R
Dehumidification control requires indirect humidifier
at DH and R. Set S4-2 as OFF. When the humidity rises
and exceeds the set value of the humidifier, the 24V
HUMIDISTAT
TO
HUMIDIFIER
TO HUMIDIFIER
HUMIDISTAT
 10. Engineering of Electrical Wring
signal of DH changes to 0V, the cooling system starts the
dehumidification operation, and the air volume drops to
80% of the nominal cooling air volume.
When the partition control, DH is connected to the DH
port of the partition controller. When the 24V signal of
DH changes to 0V, the air volume drops to 80% of the
nominal refrigeration air volume.
3.5 UV, fresh air or negative ion wiring
The WORK port is linked with the fan. When the fan
is running, the relay is closed; if an active 24V signal is
required, it can be directly connected to the G and C ports.
work
24V control signal or 208/230V power supply
4. Control Logic
Indoor unit Connector
Connector
R
C
G
Y1
Y/Y2
B
W
W1
W2
E/AUX
DH/DS/BK
L
Outdoor unit Connector
Connector
R
C
Y1
Y2
B
W
D
L
UV, fresh wind or
negative ions, etc
Purpose
24V Power Connection
Common
Fan Control
Low Cooling
High Cooling
Heating Reversing Valve
Heating Control
Stage 1 Electric heating
Stage 2 Electric heating
Emergency heating
Dehumidification/Zoning
control
System Fault Signal
Purpose
24V Power Connection
Common
Low Cooling
High Cooling
Heating Reversing Valve
Heating Control
Dehumidification control
System Fault Signal
