26
18-HD66D1-4
Section 8. Control Board Test Points
ZO
NE
S
1 - 4
5 - 8
Zone Dampers
Sensor
s
Reserved
Reserved
Reserved
Static Pres
s
Gnd/Grn
Signal/Blk
+5V/Red
Temperatur
e
Non Comm Zone Sensor
Discharge Air
Discharge Air
Return Air
Return Air
Mixed Air
Mixed Air
Zone 1 or 5
Zone 1 or 5
Zone 2 or 6
Zone 2 or 6
Zone 3 or 7
Zone 3 or 7
Zone 4 or 8
Zone 4 or 8
Zone 1 or
5
ZONES
1 - 4
5 - 8
Indoor/
Relay Panel
Comm
Outdoor
Comm Zone Sensor/
2nd Zone Panel
24V
Trans.
Common
PO/Open
PC/Closed
Zone 2 or
6
Common
PO/Open
PC/Closed
Zone 3 or
7
Common
PO/Open
PC/Closed
Zone 4 or
8
Common
PO/Open
PC/Closed
Comm
R
B
D
B
B R B
D
D
SEE TABLE 5
SEE
TABLE 1
* See Note
SEE
TABLE 4
SEE
TABLE 6
SEE
TABLE 2
SEE
TABLE 3
TABLE 2
System Connections
Terminals
Volts (DC)
Communication
Status
D & B
12
Good Communication
D & B
16
No Communication
D & B
0
Grounded or no power
TABLE 3
Power from Transformer
Terminals
Volts (AC)
Status
R & B
18 – 30
Good
R & B
< 18
Low voltage
R & B
0
No voltage
TABLE 1
Zone Dampers
Terminals
Volts (AC)
Status
Common & PO/Open
24
Damper drive open
Common & PO/Open
0
Damper not being driven
Common & PC/Close
24
Damper drive closed
Common & PC/Close
0
Damper not being driven
*
Status
LED (non-functional) may be present on early production models.