Advertisement
Section 6. LED Indicators
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.
Section 7. Troubleshooting
Symptom
Loss of 24VAC between power (R) and common (B) Check for proper incoming 24VAC power
COMM LED is not
One or more communicating devices is not com-
flashing the ap-
municating
propriate number
of devices
Loss of 24VAC between power (R) and common (B) Check for proper incoming 24VAC power
Bit Master LED is
Loss of communication
off or fluttering
Control is not calling
HVAC System
LED is not illumi-
nating when Relay
Panel is calling for
Relay Panel failed
a particular relay
18-HD68D1-10
Possible Cause
• ~12VDC between D & B = Proper communication
• ~16VDC between D & B = Loss of communication
• Less than ~12VDC between D & B = shorted or no power
• 0VDC between D & B (shorted or no power)
• Less than ~12VDC between D & B (low level short)
NORM
Dual Fuel
Switch
0
SOV
Y1 Stg1
Y2 Stg2
W1 Stg1
W2 Stg2
W3 Stg3
Fan
G
BK PWM
Hum
Hum
Aux1
Aux1
Aux2
Aux2
Troubleshooting
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
Check for shorted wire between data (D) and
common (B) wires
Check the System Report screen at the control
to verify demand
Verify 24VAC between relay output terminal and
common (B)
**Relay output contains snubber circuits; always
check with a load applied
DUAL
D
R B
Data
Hot
Com
Thermostat
and Indoor Unit
Comm
Bit Master
Relay Panel
Action
RELAY PANEL
RS
RS
ODT
ODT
27
Hide quick links:
Advertisement
