Detroit Radiant Products Company UH Series - Manual (Page 49)

49
UH Series 4.0 Troubleshooting Guide
Were the gas lines
purged of all air?
Does the heater’s gas
type match the gas
supplied?
Yes
Check manifold pressure. Are
you reading within the specified
pressures per the rating plate?
Yes
Purge gas lines.
No
Contact local
representative or factory.
No
Adjust pressure or
replace gas valve.
No
Check circuit board
for flash codes.
Consult factory.
Yes
Is the heater properly
grounded? Is the
heater’s polarity
correct?
Correct grounding or
fix polarity.
No
With a micro ammeter,
check micro-Amp reading
of flame sensor circuit. Is
it greater than 0.5 micro-
Amps? NOTE: Meter must
be connected in series.
Yes
Yes
No
Check circuit board flash
codes. Replace ignition
module.
Replace circuit board.
United Technologies Circuit Board
LED CODE
(# of flashes)
GREEN LED STATUS / ERROR
STEADY OFF Internal Control Fault or No Power
STEADY ON Control Ok
1 In Lockout from Failed Ignitions or Flame Losses
2 Pressure Switch Open with Inducer ON
3 Pressure Switch Closed with Inducer OFF
4 Limit Switch is OPEN
5 In Lockout from False Flame
LED CODE
(# of flashes)
AMBER LED STATUS / ERROR
FAST FLASH Flame Present With Gas Valve Off
STEADY ON Flame is Sensed
Fenwal Circuit Board
LED CODE
(# of flashes)
GREEN LED STATUS / ERROR
SLOW FLASH Normal Operation - No Call for Heat
FAST FLASH Normal Operation - Call for Heat
2 Ignition Lockout - No Flame Detected
3 Airflow Fault - Pressure Switch Open or Closed
4 High Limit or Rollout Switch Open
5 Flame Sense Error - Gas Valve Not Energized
STEADY ON Internal Control Failure
LED CODE
(# of flashes)
AMBER LED STATUS / ERROR
OFF Flame Signal is Below Required Level / No Flame Present
STEADY ON Flame is Sensed
LED Diagnostic Codes