I-Unit Components - Lennox ML196DF045XE36B Manual

I-UNIT COMPONENTS

ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect elec­
tronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
ML196DFE unit components are shown in figure 1. The
combustion air inducer, gas valve and burners can be ac­
cessed by removing the outer access panel. The blower
and control box can be accessed by removing the blow­
er access panel.
A-Control Box Components (Figure 2)
Unit transformer (T1) and integrated ignition control (A92)
are located in the control box. In addition, a door interlock
switch (S51) is located in the control box.
ML196DFE Control
TRANSFORMER
(T1)
CIRCUIT
BREAKER
(CB8)
INTEGRATED IGNITION
FIGURE 2
1. Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. The transformers on all
models are rated at 40VA with a 120V primary and 24V
secondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 120VAC is located on
the control box. The switch is wired in series with line volt­
age. When the blower door is removed the unit will shut
down.
Box
DOOR INTERLOCK
SWITCH (S51)
CONTROL
(A92)
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated at 3A at 32V. If the current ex­
ceeds this limit the breaker will trip and all unit operation will
shutdown. The breaker can be manually reset by pressing
the button on the face.
4. Integrated Ignition Control (A92)
Shock hazard.
Disconnect power before servicing. Control is not
field repairable. If control is inoperable, simply re­
place entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
The hot surface ignition control system consisting of an in­
tegrated control (figure 3 with control terminal designa­
tions in tables 1, 2 and 3), sensor and ignitor (figure 5). The
integrated control and ignitor work in combination to en­
sure furnace ignition and ignitor durability. The integrated
control, controls all major furnace operations. The inte­
grated control also features a RED LED for troubleshoot­
ing and two accessory terminals rated at (1) one amp. See
table 4 for troubleshooting diagnostic codes. The nitride
ignitor is made from a non-porous, high strength propri­
etary ceramic material that provides long life and trouble
free maintenance.
4-Pin Terminal Designation
PIN #
1 Combustion Air Inducer Line
2 Ignitor Line
3 Combustion Air Inducer Neutral
4 Ignitor Neutral
12-Pin Terminal Designations
PIN #
1 High Limit Output
2 Not Used
3 24V Line
4 Not Used
5 Rollout Switch Out
6 24V Neutral
7 High Limit Input
8 Ground
9 Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out
Page 6
WARNING
TABLE 1
FUNCTION
TABLE 2
FUNCTION