Lang ECCO-AP, Service Manual

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42
TROUBLESHOOTING ECCO-C CONT’D
PROBABLE CAUSE CORRECTIVE ACTION
Defective over-temp thermostat
!
Check for 24 VAC on #55 red wire to common “D” .
If 24 VAC is not measured: Turn oven off and:
!
Check for continuity through over-temp thermostat.
!
Replace if defective.
NO HEAT Computer Mode
PROBABLE CAUSE CORRECTIVE ACTION
No 24 VAC on Interface board
!
Check for 24 VAC at TP4 to ground.
If 24 VAC is not measured:
!
Check for 24 VAC at “ NC ” contacts on back-up relay.
If 24 VAC is measured:
!
Check for 24 VAC at TP6 .
!
Replace Interface board if defective.
DISPLAY LOCKS UP
PROBABLE CAUSE CORRECTIVE ACTION
“Help” in display
!
Check probe for proper resistance.
!
Check that probe connections are secure.
!
Push “TEMP” button on control board and check to see if temperature
rapidly descends. If temp does descend rapidly, replace ribbon cable.
!
Check to see that contactors/relays are not stuck in the closed
position.
!
Replace contactor if defective.
!
Check for foreign objects keeping contactor closed.