Steffes DLF40B - Manual (Page 35)

C: PROBLEM: FURNACE UNDERCHARGES
Check charge control
thermostat knob (33) for
proper position.
Set the "AUTO/HIGH/LOW" toggle switch to the "HIGH" position.
Check for proper amperage draw on heating elements (17):
DLF30B = 117 Amps (240V systems)
DLF40B = 160 Amps (240V systems)
(NOTE: Some furnaces may incorporate a Stage II Lockout feature.
If so the control circuit on these furnaces must be de­energized and
then re­energized to ensure this lockout is deactivated.
Check daily kWh usage.
Unit Undercharges on Warm Days
Unit Undercharges
on Cold Days
Less than Max Usage
Check unit sizing.
Proper Maximum
Usage
With the "AUTO/HIGH/LOW" toggle
switch still se to "HIGH" position, check
for zero voltage on charge control
resistor (66) from center to bottom and
then center to top on the resistor.
Check for 24 VAC on base terminals
of all charging sequencers (26).
Disconnect outdoor temperature
sensor (64) connection "W"
terminal block position on charge
control circuit board (30).
Replace charge control
circuit board (30).
Less Than Proper Amperage
Ok
No Voltage Present
Voltage Present Check for contact
closure on all charging
sequencers (26).
Check the "outdoor
temp SENSOR" lights on
charge control circuit board
(30). All three must be "ON".
Ok
Replace
sequencer (26).
Check heating
elements (17).
Open Ok
Check outdoor temperature
sensor (64) in cold place
(less than 15ºF). All mercury
bulbs should open.
Replace charge control
circuit board (30).
Not All Outdoor
Temperature Lights "ON" Three Outdoor
Temperature
Lights "ON"
Replace charge control
thermostat (32).
All Bulbs
Open
Replace outdoor
temperature sensor (64).
All Bulbs
Closed
Replace charge control
circuit board (30).
Check for 24 VAC on base
terminals of all charging
sequencers (26).
Ok
Voltage Present
Defective
Replace sequencer
Check unit wiring and/or
replace charge control
circuit board (30).
No Voltage
Troubleshooting Information
(cont'd)
34