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FIGURE 9
SUPPLY AIR BLOWER
AND SECONDARY LIMIT(S)
To Remove Blower From Unit: Disconnect Power, Remove
Control Box, Remove Bolts and Unplug Motor Wires From
Integrated Control. Then Slide Out Front of Unit.
SECONDARY
LIMIT (S)
CAPACITOR
MOTOR/BLOWER
ASSEMBLY
Left Side
Right Side
12. Blower Motors and Capacitors
All ML180UHA units use direct drive blower motors. All mo
tors are 230V permanent split capacitor motors to ensure
maximum efficiency. Ratings for capacitors will be on motor
nameplate. If replacing the indoor blower motor or blower
wheel is necessary, placement is critical. The blower wheel
must be centered in the blower housing as shown in figure
10. When replacing the indoor blower motor the set screw
must be aligned and tightened with the motor shaft as
shown in figure 11.
FIGURE 10
Center Blower Wheel
in Blower Housing
BLOWER WHEEL REPLACEMENT
FIGURE 11
Set Screw
Housing Hub
ALIGN AND TIGHTEN SET SCREW WITH
FLAT SIDE OF MOTOR SHAFT
Motor
Shaft
NOTE -
The 5 ton blower will have two flats
and two set screws 90° of each other .
13. Secondary Limit Controls
The secondary limit is located in the blower compartment in
the back side of the blower housing. See figure 9. When ex
cess heat is sensed in the blower compartment, the limit will
open. If the limit is open, the furnace control energizes the sup
ply air blower and closes the gas valve. The limit automatically
resets when unit temperature returns to normal. The secon
dary limit cannot be adjusted.
II- PLACEMENT AND INSTALLATION
Make sure unit is installed in accordance with installation
instructions and applicable codes.
III- START‐UP
A- Heating Start‐Up
WARNING
Shock and burn hazard.
ML180UHA units are equipped with a hot surface
ignition system. Do not attempt to light manually.
Gas Valve Operation
FIGURE 12
GAS VALVE SHOWN IN OFF POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
White Rodgers 3600 Gas Valve
