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7
DIAGNOSTIC FEATURES
The 50A55 control continuously monitors its own opera-
tion and the operation of the system. If a failure occurs, the
LED will indicate a failure code as shown below. If the
failure is internal to the control, the light will stay on
continuously. In this case, the entire control should
be replaced, as the control is not field-repairable.
If the sensed failure is in the system (external to the
control), the LED will flash in the following flash-pause
sequences to indicate failure status (each flash will last
approximately 0.25 seconds, and each pause will last
approximately 2 seconds). If more than one failure is
detected, the LED will alternate through all the failure
codes that apply.
Continuous flashing Low flame sense signal
(no pause)
1 flash, then pause Lockout caused by flame sensed
when there should be no flame
2 flashes, then pause Pressure switch stuck closed
3 flashes, then pause Pressure switch stuck open
4 flashes, then pause High limit open
5 flashes, then pause Rollout switch open or rollout
sensed
6 flashes, then pause *Lockout caused by pressure
switch opening 4 times in one
cycle
7 flashes, then pause *Lockout caused by no ignition
(after 3 trials)
8 flashes, then pause *Lockout caused by loss of flame
5 times in one heating cycle
9 flashes, then pause 115 Volt AC power reversed/
improper ground
12 flashes, then pause Ignitor relay sense error
The LED will also flash once at power-up.
* Will automatically restart from lockout after one hour. All
other conditions need to be cleared for the control to
resume normal operation.
SYSTEM LOCKOUT AND
DIAGNOSTIC FEATURES
SYSTEM LOCKOUT FEATURES
When system lockout occurs, the gas valve is de-ener-
gized, the circulator blower is energized at heat speed,
and, if flame is sensed, the inducer blower is energized.
The diagnostic indicator light will flash or glow continu-
ously to indicate system status. (System lockout will
never override the precautionary features.)
To reset the control after system lockout, do one of the
following:
1. Interrupt the call for heat or cool at the thermostat for
at least one second, but less than 20 seconds (if flame
is sensed with the gas valve de-energized, interrupt-
ing the call for heat at the thermostat will not reset the
control).
2. Interrupt the 24 VAC power at the control for at least
one second. You may also need to reset the flame
rollout sensor switch.
3. After one hour in lockout, the control will automatically
reset itself.