- 1 -
troubleshooting
guide
355MAV
Variable Speed, Two-Stage
Series H & I
Electronic
Condensing
355AAV
Gas
Furnace
355BAV
Cancels: SM05-5
SM05-07
6-08
INDEX
PAGE
Safety Considerations................................................................................. 1
Instructions.................................................................................................. 1
Example ...................................................................................................... 2
General........................................................................................................ 2
Sequence of Operation ............................................................................... 2
Single-Stage Thermostat and Two-Stage Heating (Adaptive
Mode) ................................................................................................. 2
Two-Stage Thermostat and Two-Stage Heating .............................. 4
Cooling
Mode .................................................................................... 4
Single-Speed
Cooling ........................................................................ 4
Single-Stage Thermostat and Two-Speed Cooling (Adaptive
Mode) ................................................................................................. 4
Two-Stage Thermostat and Two-Speed Cooling ............................. 5
Thermidistat Mode............................................................................. 5
Super-Dehumidify Mode................................................................... 5
Continuous-Blower Mode ................................................................. 6
Heat Pump Defrost............................................................................. 6
Component Test................................................................................. 6
Service/Status Code Instructions ............................................................... 7
Start Here .................................................................................................... 9
Rapid Flashing AMBER LED................................................................. 10
Improper Cooling Air Flow ..................................................................... 11
High Heat Temperature Rise Too Low ................................................... 12
Status Code 11 - No Previous Code......................................................... 13
Status Code 12 - Blower On After Power Up ......................................... 13
Status Code 13 - Limit Circuit Lockout .................................................. 14
Status Code 14 - Ignition Lockout........................................................... 15
Status Code 15 – Blower Motor Lockout................................................ 15
Status Code 21 - Gas Heating Lockout.................................................... 15
Status Code 22 - Abnormal Flame-Proving Signal................................. 16
Status Code 23 - Pressure Switch Did Not Open .................................... 16
Status Code 24 - Secondary Voltage Fuse Is Open................................. 17
Status Code 25 – Model Selection or Setup Error................................... 19
Status Code 31 – High-Heat Switch or Relay did not close or
Reopen.............................................................................................. 19
Status Code 32 - Low-Heat Pressure Switch Did Not Close or
Reopened.......................................................................................... 21
Status Code 33 - Limit Circuit Fault........................................................ 23
Status Code 34 - Ignition-Proving Fault.................................................. 25
Status Code 41 – Blower Motor Fault ..................................................... 26
Status Code 42 – Inducer Motor Fault..................................................... 28
Status Code 43 - Low-Heat Pressure Switch Open While High-Heat
Pressure Switch Is Closed................................................................ 30
Status Code 45 – Control Circuitry Lockout........................................... 31
Cleanup and Start-Up Instructions........................................................... 31
APPENDIX A - Board Layout & Wiring Schematic ............................. 32
APPENDIX B - ECM Blower Motor Description & Operation............ 36
APPENDIX C - Pressure Check Diagram .............................................. 37
APPENDIX D - Static Pressure Reading Location Diagrams................ 38
APPENDIX E - Quick Reference Information ....................................... 40
APPENDIX F - Furnace Staging Algorithm........................................... 41
SAFETY CONSIDERATIONS
Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified personnel
should install, repair, 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 literature, on tags, and on
labels attached to or shipped with the unit, and other safety
precautions that may apply.
Follow all safety codes. In the United States, follow all safety codes
including the National Fuel Gas Code (NFGC) NFPA 54-2006/ANSI
Z223.1-2006. In Canada, refer to the National Standard of Canada
Natural Gas and Propane Installation Codes (NSCNGPIC), CSA
B149.1-05.
Wear safety glasses and work gloves. Have a fire extinguisher
available during start-up, adjustment procedures, and service calls.
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,
and NOTE. The words DANGER, WARNING, and CAUTION are
used with the safety-alert symbol. DANGER identifies the most
serious hazards which will result in severe personal injury or death.
WARNING signifies hazards which could result in personal injury or
death. CAUTION is used to identify unsafe practices which may
result in minor personal injury, or product and property damage.
NOTE is used to highlight suggestions which will result in enhanced
installation, reliability, or operation.
INSTRUCTIONS
This guide uses your expertise and observations to lead you to the
trouble spot as efficiently as possible. This is only intended as a guide
and should not be used blindly. Your experience and expertise are of
high value when troubleshooting this unit. Do not disregard all of
your instincts.
The variable speed furnace control was designed with diagnostic
capabilities built in. A AMBER LED is used to flash a status code
which will lead you to one of the sections as listed in the Index.
You should ALWAYS begin in the START HERE section (see Index
for page number) which will guide you to the appropriate section
where a minimal number of steps will be used to correct the problem.
Once in a section, read the ACTION. An ACTION may have a
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