Printed in U.S.A. 440 04 4321 04 July 2012
SERVICE AND TECHNICAL
SUPPORT MANUAL
Two−Stage, ECM Blower Motor
35” Tall, High Efficiency Condensing Gas Furnace
(F/G)9MXT
Save this manual for future reference.
Safety Labeling and Signal Words
DANGER, WARNING, CAUTION, and NOTE
The signal words DANGER, WARNING,
CAUTION, and NOTE are used to identify levels of
hazard seriousness. The signal word DANGER is
only used on product labels to signify an immediate
hazard. The signal words WARNING, CAUTION,
and NOTE will be used on product labels and
throughout this manual and other manual that may
apply to the product.
DANGER − Immediate hazards which will result in
severe personal injury or death.
WARNING − Hazards or unsafe practices which
could result in severe personal injury or death.
CAUTION − Hazards or unsafe practices which
may result in minor personal injury or product or
property damage.
NOTE − Used to highlight suggestions which will
result in enhanced installation, reliability, or
operation.
!
WARNING
Signal Words in Manuals
The signal word CAUTION is used throughout
this manual in the following manner:
!
CAUTION
Signal Words on Product Labeling
Signal words are used in combination with
colors and/or pictures or product labels.
The signal word WARNING is used throughout
this manual in the following manner:
Safety−alert symbol
When you see this symbol on the unit and in
instructions or manuals, be alert to the
potential for personal injury.
TABLE OF CONTENTS
START−UP, ADJUSTMENT, AND SAFETY CHECK 4...........
THERMOSTAT SETUP SWITCH 4...........................
PRIME CONDENSATE TRAP WITH WATER 4.................
PURGE GAS LINES 4......................................
ADJUSTMENTS 5.........................................
ADJUST TEMPERATURE RISE 10............................
ADJUST BLOWER OFF DELAY (HEAT MODE) 11..............
ADJUST COOLING AIRFLOW 11.............................
ADJUST CONTINUOUS FAN AIRFLOW 11....................
ADJUST THERMOSTAT HEAT ANTICIPATOR 11...............
CHECK SAFETY CONTROLS 12.............................
CHECKLIST 12.............................................
SERVICE AND MAINTENANCE PROCEDURES 13.............
ELECTRICAL CONTROLS AND WIRING 13...................
TROUBLESHOOTING 13....................................
CLEANING AND/OR REPLACING AIR FILTER 15..............
BLOWER MOTOR AND WHEEL MAINTENANCE 15............
CLEANING BURNERS AND FLAME SENSOR 17...............
SERVICING HOT SURFACE IGNITER 18......................
FLUSHING COLLECTOR BOX AND DRAINAGE SYSTEM 18....
CLEANING CONDENSATE DRAIN AND TRAP 19..............
CLEANING HEAT EXCHANGERS 19..........................
SERVICE LABEL 21.........................................
WIRING DIAGRAM 22.......................................
SEQUENCE OF OPERATION 25.............................
PARTS REPLACEMENT INFORMATION GUIDE 29.............
PRODUCT NOMENCLATURE 30.............................
MODELS
(F/G)9MXT0401410A
(F/G)9MXT0601714A
(F/G)9MXT0801716A
(F/G)9MXT0802120A
(F/G)9MXT1002120A
(F/G)9MXT1202422A
Use of the AHRI Certified TM Mark indicates a
manufacturer’s participation in the program.
For verification of certification for individual
products, go to www.ahridirectory.org .
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