Steffes DLF40B - Manual (Page 32)

Troubleshooting Information
(cont'd)
31
Core Charging
A. PROBLEM: FURNACE OVERCHARGES ON WARM DAY
Check operation of outdoor
temperature lights on charge
control circuit board (30).
Check "AUTO/HIGH/LOW" toggle switch. Unit
should not be in HIGH mode on warm days.
All Outdoor Temperature Lights Are "ON"
Regardless of Outdoor Temperature
With wires disconnected, check ohm
values of the resistor (66). Must be 175
ohm center to top & center to bottom.
Check for 32 VDC between room thermostat
connection "C" terminal block position and top low
voltage 1/2­amp fuse on charge control circuit
board (30). Check fuse.
Replace
resistor (66).
Check VAC on resistor (66) from middle to top and middle to
bottom. Reults vary depending on number of charging lights
on:
1 light on = 24 VAC middle to top and bottom
2 lights on = 0 VAC middle to top; 24 VAC middle to bottom
3 lights on = 0 VAC middle to top and bottom
Lights Work Properly
Ok
Defective
No Voltage
Fuse Ok
Check for 24 VAC between room thermostat
connection "C" terminal block position and the
two 3­amp low voltage fuses on the charge
control circuit board (30).
Replace charge
control thermostat.
Check control
transformers (28).
Replace charge control
circuit board (30).
No Voltage
Present
Ok
Replace charge control circuit board (30).
Ok
1. With outdoor temperature sensor wiring disconnected, the
"SUMMER/WINTER" toggle switch on charge control circuit board (30) set to the
WINTER position and the "AUTO/HIGH/LOW" toggle switch set to "AUTO",
jumper outdoor sensor terminal block positions "W" & "R". "LEVEL 3 OUTDOOR
TEMP SENSOR" light on charge control circuit board (30) should be off.
2. Jumper "W", "R", & "B" terminal block position. "LEVEL 2 AND 3 OUTDOOR
TEMP SENSOR" lights on charge control circuit board (30) should go off.
Voltage
Present
Replace charge control
circuit board (30).
Replace outdoor
temperature sensor (64)
Defective Ok
Check unit wiring and
the charge control
circuit board fuses.
Repair wiring or replace fuses.
NOTE: If fuses open again,
change charge control circuit
board (30).
Incorrect Wiring
or Open Fuse(s)
Ok
Incorrect
Replace charge control
circuit board (30).
Ok