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Five Flashes – Twin Communication Fault
The information below is related to situations where the troubleshooting code ashes
FIVE times:
Twin Communication Fault:
• Occurs if the 24 VAC supply to the twins are not in phase with each other or
power is removed from one of the twins.
• While a twin fault exists, the control does not respond to thermostat
commands, and the green light will ash ve times.
– Open limit and undesired ame response are still operational
– The control continually tries to establish communication and automatically
resumes normal operation when communication is re-established
– If a twin fault occurs during a heat cycle, both furnaces will terminate the
call immediately
– The only chance for blower mis-synchronization is if the blower off delays
are set differently on the twins
– If a twin fault occurs during high speed fan or continuous fan operation,
both controls will shut the blowers off immediately.
– If a twin communication terminal is not in use and the unit is showing a
troubleshooting code of ve ashes, the board may be defective.
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