A
DJM3
IOM-17
26 of 27 Mar 99 R3
HEAT
OPERATION
FLOWCHART
Main Supply power ‘ON’
Service Switch ‘ON’
Fire alarm contact ‘CLOSED’
24Vac on T1,T2
24Vac on FS,HS
Heat call
light ’ON’?
PP light
’ON’?
Heat call
light ’2 SEC
FLASH’?
No heat call
Restore 24Vac
to ‘HS’
Any lights
Flashing?
Indicates
possible
lockout
10 Vdc on
terminals
‘O’ or ‘G’?
Combustion
fan started?
Pre‐Purge
light ‘2 SEC
FLASH’?
Faulty DJM3
Faulty combustion fan
No output from terminal
’CB’
Speed Sensor
Problem
Combustion fan
running with 5
Vdc across
terminals ‘YS’ and
DJM3 fuse
failure or faulty
DJM3
Turn over
magnet or
replace
If 0 or 10 Vdc across ‘YS’ and ‘G’
with Combustion fan running,
replace speed sensor
Ignition
Enable light
‘ON’?
Unit stuck in
Pre‐Purge
Power goes to Ignition
Control, burner will
light. Once DJM3
receives feedback signal,
firing rate will modulate.
Normal operation
YES
YES
YES
NO
NO
NO
YES
YES
NO
NO
YES
YES
YES
NO
NO
NO
YES
NO