From inside (document excerpt):
High Output PSC Inducer Motor Housing Assembly Kit Cancels: IIK 340M-40-49 IIK 340M-40-53 7-98 Installation Instructions Part No. 320725-754 and 755 NOTE: Read the entire instruction manual before starting the installation. This symbol indicates a change since the last issue. SAFETY CONSIDERATIONS Installing and servicing of heating equipment can be hazardous due to gas and electrical components. Only trained personnel should install or service heating equipment.
Untrained personnel can perform basic maintenance functions such as cleaning coils or cleaning and replacing filters. All other operations should be performed by trained service personnel. When working on heating equipment, observe precautions in the literature, on tags, and on labels attached to the unit. Follow all safety codes. Wear safety glasses and work gloves. Have fire extinguisher available. Recognize safety information. This is the safety-alert symbol. When you see this symbol on the furnace and in instructions or manuals, be alert to the potential for personal injury. Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies a hazard which could result in personal injury or death. CAUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage. INTRODUCTION This instruction covers installation of the high output permanent split capacitor (PSC) inducer motor kit Part No. 320725-754 and 320725-755 on models 340MAV, 345MAV, 350MAV, 490AAV, 58MCA, 58MSA, 58MXA, PG9MAA Condensing Gas Furnaces. See Table 1 for kit applicability. DESCRIPTION AND USAGE Use this PSC inducer motor kit to replace a failed inducer motor assembly. This kit contains the following items: Inducer assembly 1 Installation Instructions 1 NOTE: Inducer assembly consists of motor and fan, capacitor, wheel, motor mount, inducer cover, inducer housing, vent cap, and vent clamp. INSTALLATION Step 1–Remove Old Motor Assembly 1. Turn off gas and electrical supplies to unit. 2. Remove main furnace door. 3. Remove drain tube from inducer motor mounting cover plate. 4. Remove pressure switch tubes. (See Fig. 1.) a. Remove tube attached to pressure switch from collector box. Before beginning any installation or modification, be sure the main electrical disconnect switch is in the OFF position. Electrical shock can cause personal injury or death. b. Remove tube attached to pressure switch from burner enclosure and gas valve. 5. Remove screw securing pressure switch and capacitor to inducer housing. 6. Disconnect motor lead connector from quick-connect. 7. Using backup wrench, disconnect gas supply pipe from gas valve. 8. Remove wires from gas valve. Note location for reassembly. 9. Remove burner box cover. 10. Remove screws securing manifold to burner box.