Thermo Products GMD1-60N, GDM1-80N Diagnostic Features, The LED will also flash once at power-up

All installations and services must be performed by qualified service personnel.

DIAGNOSTIC FEATURES

: Power must be disconnected before servicing.

The 50A65-143 control continuously monitors its own operation 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).

1 flash, then pause	System lockout
2 flashes, then pause	Pressure switch stuck closed
3 flashes, then pause	Pressure switch stuck open
4 flashes, then pause	Open limit switch or rollout switch
6 flashes, then pause	115 Volt AC power reversed
7 flashes, then pause	Low flame sense signal
8 flashes, then pause	Check igniter or improper grounding
Continuous flashing	Flame has been sensed when
(No pause)	no flame should be present
	(No call for heat)

The LED will also flash once at power-up.

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