11
INSSCV1217
CIR-019 CONTROL BOARD FUNCTIONS
The CIR-019 control board is used with all air handler models using a PSC motor (model # SCV-P-xxxx). The following figure represents the
control board:
Input and output descriptions
The terminal block of the control unit fan housing (shown on the right side of Fig. 9) has the following inputs and outputs:
• R: 24Vac output (18VA max) can supply an external controller or thermostat
• C: Common internal transformer
• 3: High speed control signal (24Vac)
• 2: Medium speed control signal (24Vac)
• 1: Low speed control signal (24Vac)
Priority input controls
The highest selected speed is systematically prioritized. For example, if the input of the low speed and medium are activated simultaneously, the
medium speed will be prioritized.
TYPICAL THERMOSTAT CONNECTION
The following figure shows a typical connection with a 24Vac thermostat. For more clarity, the air handler cabinet is not shown on this fig. If
needed, refer to Fig. 9 to see the entire connection path.
R
R
C
3
3
2
2
1
1
24V
HIGH
MEDIUM
LOW
R
R
C
3
3
2
2
1
1
R
C
Y
W
G
THERMOSTAT
R
R
C
3
3
2
2
1
1
DETAIL A
R
C
Y
W
G
AIR
HANDLER
THERMOSTAT
FIG. 10
FIG. 11
