RELAY PANEL
18-HD68D1-10 27
Section 7. Troubleshooting
Troubleshooting
Symptom
Possible Cause
Action
COMM LED is not
flashing the ap-
propriate number
of devices
Loss of 24VAC between power (R) and common (B) Check for proper incoming 24VAC power
One or more communicating devices is not com-
municating
•
~12VDC between D & B = Proper communication
•
~16VDC between D & B = Loss of communication
•
Less than ~12VDC between D & B = shorted or no power
Check for open or shorts in field wiring
Evaluate other communicating devices and use
the service facts of that device if not communi-
cating properly
Bit Master LED is
off or fluttering
Loss of 24VAC between power (R) and common (B) Check for proper incoming 24VAC power
Loss of communication
•
0VDC between D & B (shorted or no power)
•
Less than ~12VDC between D & B (low level short)
Check for shorted wire between data (D) and
common (B) wires
HVAC System
LED is not illumi-
nating when Relay
Panel is calling for
a particular relay
Control is not calling
Check the System Report screen at the control
to verify demand
Relay Panel failed
Verify 24VAC between relay output terminal and
common (B)
**Relay output contains snubber circuits; always
check with a load applied
Section 6. LED Indicators
Aux2
Relay Panel
Bit Master
Comm
HV
AC System
Sensor
s
Thermostat
and Indoor Unit
Outdoor
Remote
Data
Hot
Com
D R B
Indoo
r
RS
RS
ODT
ODT
24
Va
c
Onl
y
24
Va
c
Onl
y
24
Va
c
Only
Aux2
Aux1
Aux1
Hum
Hum
BK PWM
Fan
G
W3 Stg3
W2 Stg2
W1 Stg1
Y1 Stg1
Y2 Stg2
0 SOV
NORM
Dual Fuel
Switch
DUAL
Comm
Communication LED – Amber
• LED on when first powering up
• LED flashes number of communicating com-
ponents in the system.
• (ex. communicating control with relay panel
will equal two flashes)
Bit Master
Bitmaster/Clock Signal LED – Green
• LED on when Clock is working
HVAC System
HVAC System LEDs – Green
• A Green LED will illuminate when the relay is
energized.
