Lenox ML180UH110AP36C - I Unit Components

Page 6
I-UNIT COMPONENTS
ML180UHA unit components are shown in figure 1.The
gas valve, combustion air inducer and burners can be ac
cessed by removing the upper access panel. Electrical
components are in the control box (figure 2) found in the
blower section.
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.
1. Control Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. Transformers on all
models are rated 40VA with a 230V primary and a 24V sec
ondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 230VAC is wired in se
ries with line voltage. When the blower door is removed the
unit will shut down.
FIGURE 2
CONTROL BOX ML180UHA
Integrated Control
Door Interlock Switch
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box.
The switch provides overcurrent protection to the trans
former (T1). The breaker is rated 3A at 32V. If the current
exceeds this limit the breaker will trip and all unit opera
tion will shutdown. The breaker can be manually reset
by pressing the button on the face. See figure 3.
FIGURE 3
CIRCUIT BREAKER CB8
PRESS TO RESET
4. Integrated Control (A92)
WARNING
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 re
sult if repair is attempted.
The hot surface ignition control system consisting of an in
tegrated control (figure 4 with control terminal designa
tions in tables 1 and 2.) sensor and ignitor (figure 6). 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 one LED light (AN1 red) for
troubleshooting and two accessory terminals rated at (1)
one amp. The integrated control also features a (3) amp
fuse for overcurrent protection. See table 3 for trouble
shooting diagnostic codes. The nitride ignitor is made
from a non-porous, high strength proprietary ceramic ma
terial that provides long life and trouble free maintenance.
The integrated control continuously monitors line voltage
and maintains the ignitor power at a consistent level to
provide proper lighting and maximum ignitor life.