Lennox 21P12 Installation Instructions

©2024
INSTALLATION INSTRUCTIONS FOR BLOWER ASSEMBLY REPLACEMENT KIT
Shipping and Packing List
Package 1 of 1 contains:
1- Blower assembly
WARNING
Improper installation, adjustment, alteration, ser­
vice or maintenance can cause property damage,
personal injury or loss of life. Installation and ser­
vice must be performed by a licensed professional
HVAC installer or equivalent, service agency, or the
gas supplier
Application
The blower assembly replacement kit is used on LG/LC/
LH/LD 024 - 074 units. See TABLE 1.
TABLE 1
Cat. No.
21P12/27H86 621654-01/621654-07
21P13/27H89 621654-02/621654-08
21P15*/27H90 621654-03/621654-09
21P17*/27H91 621654-04/621654-10
*Corrosion protection
Installation
1 - Disconnect electrical power to unit. Wait five minutes
before continuing service procedures to avoid elec-
trical shock. This will allow internal capacitors time to
fully discharge.
2 - Open access panels as shown in FIGURE 1.
3 - Disconnect J48 from P48 in the blower area and un-
screw the GND terminal from the blower deck.
4 - Disconnect the Modbus 9-pin blower control plug lo-
cated in the blower area.
5 - Remove four screws securing blower assembly to
unit. See FIGURE 2.
6 - If unit was equipped with a blower proving switch,
remove switch from existing blower housing. Attach
the proving switch to replacement housing in the
same manner it was removed.
PACKAGED UNITS -
KITS
508119-02
4/2024
Supersedes 508119-01
USED WITH LG/LC/LH/LD 024-074 UNITS
Assembly No. Voltage
G, J
G, J
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.
Y
7 - When present, remove PT6 pressure transducer
Y
bracket and silicone tubing from housing. See FIG-
URE 2. If needed, remove the inlet ring to disconnect
the tubing from the inlet ring barb. See FIGURE 3.
Disconnect the pressure transducer wire connector.
8 - Use the handle on the blower assembly to slide the
assembly out of unit.
9 - When removed, attach the pressure transducer
bracket, wire connector, and silicone tubing to the
replacement housing in reverse order of removal.
10 - Install replacement blower assembly flanges into
rails on the blower deck in the same manner it was
removed. Secure into place using four screws shown
in FIGURE 2.
11 - Uncoil P48 and Modbus 9-pin blower control wiring
harnesses secured to replacement blower housing.
See FIGURE 4.
12 - Connect P48 to J48 in blower compartment. Screw
GND terminal to blower deck in the same manner it
was removed.
13 - Connect the Modbus plug in the blower area to the
replacement blower motor 9-pin control plug.
14 - Bundle harnesses and use wire ties to secure kit
harnesses to unit harnesses in the same manner
they were removed.
Page 1
BLOWER ASSEMBLY
REPLACEMENT KIT
UNIT ACCESS
BLOWER
ACCESS
FIGURE 1
CAUTION
CONTROL
ACCESS