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SYSTEM LOCKOUT AND
DIAGNOSTIC FEATURES
SYSTEM LOCKOUT FEATURES
When system lockout occurs, the gas valve is de-energized, the
circulator blower is energized at heat speed, and, if flame is
sensed, the inducer blower is energized. The diagnostic indica-
tor light will flash or glow continuously to indicate system status.
(System lockout will never override any 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, interrupting 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.
DIAGNOSTIC FEATURES
The 50A55 control continuously monitors its own operation and
the operation of the system. The LED light on the control will
flash slowly (one flash per second) if there are no failures and no
call for heat. If there is a call for heat, the LED will flash quickly
(one flash per half-second). 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 LED is continuously off, there may
be no power to the control; the fuse on the control may be open;
or there may be a failure in the control.
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).
2 flashes, then pause System lockout (no flame)
3 flashes, then pause Pressure switch problem
4 flashes, then pause Thermal protection device open
5 flashes, then pause Flame sensed with gas valve off
6 flashes, then pause 115 Volt AC power reversed/im-
proper ground
7 flashes, then pause Gas valve circuit error
8 flashes, then pause Low flame sense signal
The LED will also flash once at power-up.