Service manual

NO HEAT ON DJM-3
The following is a flow chart covering many general operating/troubleshooting situations.
If a more detailed manual is needed, contact the nearest EngA factory.
- Unit is in prepurge
- Comb. Blower slows to light off speed.
ignition enable light should come on
within 45 sec. (max. 60 sec.)
Yes No
Is Ign. Enable
light on?
Yes No
Are any lights on or flashing?
Yes No
Prepurge light flashing?
Yes No
Is heat call light SOLID ON upon
call for heat?
Yes No
Did combustion
fan start?
Yes No
Heat call light 2 sec. flash?
Yes No
- Restore power
- Check line voltage
24 VAC on T
1
T
2
Yes No
Is PP light SOLID ON?
Yes No
Check for 10 VDC power on O or G
Yes No
Is 5 VDC across
terminals “YS and G”
while comb. fan runs
Yes No
Is zero or 10 volts across
terminals “YS and G” while
combustion fan runs - yes?
Power goes to burner
supervision relay. It lights
and supervises pilot.
After it sends feedback
signal to DJM terminal 3,
DJM will modulate comb.
Fan and gas - normal
operation.
- Faulty Comb. Fan
motor, fuse, power
- No output from
DJM “CB” terminals
Suspect faulty DJM-3.
Replace DJM-3
Unit stuck in
pre-purge
Restore Power
to ‘HS’
No heat called for
Replace
Speed
Sensor
Review following steps as
there is a problem with
combustion motor or speed
sensing. See DJM-3.2
manual for more information.
DJM fuse failed or
DJM is faulty
Speed
Sensor
operates
but signal not
good - turn
magnet over
or replace it.
This may indicate
certain lockout
has taken place.
Refer to chart at
top of this page.
Suspect faulty DJM-3.
Replace DJM-3
LED ON 2 SEC. FLASH 1 SEC. FLASH INT. FLASH
LL Lockout Low Limit Bypass Discharge Sensor Open -
Prepurge Prepurge Problem - Service Mode
Heat Call HT Switch Open - -
Ignition Enabled - Flame Failure -
Dip switch #5 should be off for this quick test.