Bryant 355MAV Troubleshooting Manual
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Bryant 355MAV Troubleshooting Manual

Series h & i variable speed, two-stage electronic condensing gas furnace
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See also: User's Information Manual
Safety Considerations................................................................................. 1
Instructions.................................................................................................. 1
Example ...................................................................................................... 2
General........................................................................................................ 2
Sequence of Operation ............................................................................... 2
Mode) ................................................................................................. 2
Two-Stage Thermostat and Two-Stage Heating .............................. 4
Cooling Mode .................................................................................... 4
Single-Speed Cooling ........................................................................ 4
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
Reopen.............................................................................................. 19
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
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 C - Pressure Check Diagram .............................................. 37
APPENDIX E - Quick Reference Information ....................................... 40
APPENDIX F - Furnace Staging Algorithm........................................... 41
troubleshooting guide
Variable Speed, Two-Stage
Electronic Condensing
Gas Furnace
INDEX
PAGE
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.
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
- 1 -
355MAV
Series H & I
355AAV
355BAV
Cancels:
SM05-5

SAFETY CONSIDERATIONS

INSTRUCTIONS

SM05-07
6-08
.
!

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  • Page 1: Table Of Contents

    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 Safety Considerations................. 1 Instructions....................1 Installing and servicing heating equipment can be hazardous due to Example ...................... 2 gas and electrical components.

  • Page 2: Example

    number in the GO TO column. Do whatever the ACTION says, then Let’s try our guide out using the EXAMPLE section below, and see proceed to the step indicated in the GO TO column. how it works. Suppose that the problem is a defective low heat pressure switch (for example the contacts will not open).
  • Page 3 Inducer Prepurge Period - The furnace control CPU turns on inducer motor IDM and slowly increases the 355MAV and 355AAV – 60 seconds after the gas valve inducer motor speed. When the low-heat pressure switch GV-M is opened the blower motor BLWM is turned ON at LPS closes, inducer motor RPM is noted by the furnace low-heat airflow.

  • Page 4: Two-Stage Thermostat And Two-Stage Heating

    TWO-STAGE THERMOSTAT AND TWO-STAGE blower motor BLWM will continue operating at cooling HEATING airflow for an additional 90 seconds. Jumper Y/Y2 to DHUM to reduce the cooling off-delay to 5 seconds. (See Note: In this mode the low-heat only switch SW1-2 must be Fig.

  • Page 5: Two-Stage Thermostat And Two-Speed Cooling

    cooling airflow which is the true on-board CF selection as furnace control on the DHUM input, the furnace control shown in Table 1. operates in Thermidistat mode. If the DHUM input is low for more than 48 hours, the furnace control reverts back to non- If the furnace control CPU switches from low-cooling to Thermidistat mode.

  • Page 6: Heat Pump Defrost

    blower motor BLWM will remain ON until the main burners signals disappear at the same time, the blower motor BLWM ignite then shut OFF and remain OFF for the blower-ON delay will remain on at low-heat airflow for the selected blower-OFF (60 seconds in low-heat, and 35 seconds in high-heat), allowing delay period.

  • Page 7: Service/Status Code Instructions

    SERVICE/STATUS CODE INSTRUCTIONS If status code recall is needed disconnect the “R” thermostat lead, reset power, and put setup switch “SW1-1” in the ON position. To clear the status code history put setup switch “SW1-1” in the ON position and jumper thermostat terminals “R”, “W/W1”, and “Y/Y2” simultaneously until status code #11 is flashed.

  • Page 8: Component Test

    33 LIMIT CIRCUIT FAULT – Indicates the limit, or flame rollout is open or the furnace is operating in high-heat only mode due to 2 successive low heat limit trips. Blower will run for 4 minutes or until open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #13.

  • Page 9: Start Here

    START HERE - If a problem exists, the service technician should always begin troubleshooting here. SPECIAL NOTE: ALL VOLTMETERS ARE NOT THE SAME - YOUR VOLTAGE READINGS WILL VARY. THIS APPLIES TO THE ENTIRE CONTENT OF THIS TROUBLESHOOTING MANUAL. THEY ARE NOT ABSOLUTE VALUES. CORRECT 115-VAC VOLTAGE, CURRENT, AND POWER MEASUREMENTS CANNOT BE TAKEN ON VARIABLE SPEED FURNACES UNLESS USING A TRUE RMS METER.

  • Page 10: Rapid Flashing Amber Led

    STEP ACTION GO TO Is 115-vac across the transformer leads? Replace the transformer. Is 24-vac across W/W1 and C -24V on the variable speed furnace control? You will not be able to check for voltage across W/W1 and C -24V if the furnace is connected to a User Interface at the ABCD connector.

  • Page 11: Improper Cooling Air Flow

    IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not properly connected. If User Interface is connected to ABCD connector then the wrong size outdoor unit could be configured in the User Interface. STEP ACTION GO TO Remove blower access panel and depress door switch.

  • Page 12: High Heat Temperature Rise Too Low

    Table 2 – Cooling Tonnage vs. Airflow (CFM) AIR CONDITIONING TONS AIRFLOW 040, 060, & 3T- 5T-080 & 100 120 MODEL (12,000 BTU/HR) (CFM) 080 MODEL MODEL 1-1/2 2-1/2 1050 3-1/2 1225 1400 1750 2100 AIR CONDITIONING (A/C) OR CONTINUOUS-FAN (CF) AIRFLOW SELECTION CHART BASED ON 350 CFM/TON (SETUP SWITCH SW1-5 OFF) SETUP SWITCH SW3 POSITIONS...

  • Page 13: Status Code 11 - No Previous Code

    STEP ACTION GO TO Ensure the gas inlet pressure and burner orifice are correct. Then adjust the gas valve to the proper rate. If it cannot be adjusted to the proper rate, replace the gas valve. Is outdoor condensing unit operating during heating cycle? Check temperature rise and external static pressure with blower access panel in place.

  • Page 14: Status Code 13 - Limit Circuit Lockout

    STEP ACTION GO TO Disconnect the R thermostat lead. Do you have less than 19-vac across R and C -24V on the variable speed furnace control? Replace transformer. The thermostat and/or thermostat wires are loading down the transformer. Replace the thermostat or repair thermostat wires.

  • Page 15: Status Code 14 - Ignition Lockout

    STEP ACTION GO TO Replace flame rollout switch FRS. Reset flame rollout switch FRS, turn power on, and observe furnace operation for (2) 15 minute cycles. Does the flame rollout switch FRS trip again? Does a different status code flash? You have inadequate combustion-air supply.

  • Page 16: Status Code 22 - Abnormal Flame-Proving Signal

    STEP ACTION GO TO Go to page number indicated in the Index for the section covering the status code. INDEX Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. Jumper R and W/W1 thermostat terminals. Does status code 21 start flashing when the low heat pressure switch LPS makes? Replace the variable speed furnace control.

  • Page 17: Status Code 24 - Secondary Voltage Fuse Is Open

    STEP ACTION GO TO Replace variable speed furnace control. Is the low heat pressure switch LPS wired correctly? Replace the pressure switch assembly. Is the high heat pressure switch HPS wired correctly? Rewire high heat pressure switch HPS per wiring diagram. Replace the pressure switch assembly and replace the variable speed furnace control.
  • Page 18 STEP ACTION GO TO Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage fuse. Disconnect BLUE wire to gas valve GV and jumper R and W/W1 thermostat terminals. Does status code 34 flash? If not, status code 24 should occur when BLUE wire is energized. Turn power off and disconnect PL1 from variable speed furnace control.

  • Page 19: High-Heat Pressure Switch Or Relay (Code 31)

    Status Code 25 MODEL SELECTION OR SETUP ERROR – If status code 25 only flashes 4 times on power-up the variable speed furnace control is missing its model plug (PL4) and is defaulting to the model selection stored in memory. If status code 25 flashes continuously it could indicate any of the following: Model plug (PL4) is missing and there is no valid model stored in permanent memory.
  • Page 20 - HIGH HEAT PREPURGE - If the high heat pressure switch HPS does not make within 45 seconds after the low-heat pressure switch LPS made the variable speed begins flashing status code 31, shuts unit down, waits 2 minutes, stops flashing status code 31, and restarts heating cycle. If high heat pressure switch HPS opens before ignition, the variable speed starts flashing status code 31 and ramps inducer RPM up until the high heat pressure switch HPS remakes.

  • Page 21: Low-Heat Pressure Switch (Code 32)

    STEP ACTION GO TO Is inducer wheel okay? If possible, replace inducer wheel. Otherwise, replace inducer motor assembly. Is the inducer wheel properly mounted to the inducer motor shaft? Is there any frost build-up on the combustion-air inlet? Fix problem. You have excessive restriction in combustion-air or vent pipe.
  • Page 22 STEP ACTION GO TO You have an open wire or bad terminal on the YELLOW wire from the variable speed furnace control to the low heat pressure switch LPS. Repair or replace the main wire harness. Replace the variable speed furnace control. At start of cycle as inducer is ramping up, does low heat pressure switch LPS make then break? The problem is either a sag in vent pipe or a clogged drain trap or line.

  • Page 23: Status Code 33 - Limit Circuit Fault

    Status Code 33 LIMIT CIRCUIT FAULT - This status code indicates the limit, or flame rollout switch is open or the furnace is operating in high- heat only mode due to 2 successive low heat limit trips. Blower will run for 4 minutes or until the open switch remakes whichever is longer.
  • Page 24 STEP ACTION GO TO Remove tape from door switch, turn power off at main disconnect, and remove jumper across R and W/W1. Is the blower wheel firmly mounted on motor shaft? Does the model plug PL4 match the part number specified on the Model Plug Chart in the upper left hand corner of wiring schematic? Replace model plug.

  • Page 25: Status Code 34 - Ignition-Proving Fault

    Status Code 34 IGNITION-PROVING FAULT - This status code indicates flame was not sensed during trial for ignition period. The control will repeat ignition sequence 3 more times before going to status code 14 - IGNITION LOCKOUT. This status code can also indicate flame signal was lost during steady-state operation.

  • Page 26: Status Code 41 - Blower Motor Fault

    STEP ACTION GO TO Clean flame sensor with fine sandpaper and make sure it is properly positioned then recheck current. Current is typically 4.0 to 6.0 microamps. Is current near typical value? Replace electrode. Will main burners ignite and stay on? Do you have burner pulsation’s? Check the following: - Make sure perforated disks are in combustion-air vent inlet.
  • Page 27 STEP ACTION GO TO Replace the entire blower motor or blower control module attached to the blower motor. If you replace the blower control module go to step 36. Always inspect failed motor for water damage. If present, find source of water and fix it. Check A-coil and/or humidifier. Disconnect jumper wire across R and W/W1 thermostat terminals.

  • Page 28: Status Code 42 - Inducer Motor Fault

    STEP ACTION GO TO Does the voltage fluctuate as described in step 28? Reconnect PL3 to the variable speed furnace control and connect a DC voltmeter across terminals PL3-4 BLUE (+) and PL3-2 GREEN (-). Does the voltage fluctuate as described in step 28? Disconnect PL13 from the blower motor and connect a DC voltmeter across the BLUE (+) and GREEN (-) wires at connector PL13.
  • Page 29 STEP ACTION GO TO Hook an AC voltmeter across PL2-4 and NEUTRAL-L2 on the variable speed furnace control. Is 115-vac across PL2-3 and NEUTRAL-L2? Replace the variable speed furnace control. Do you have 115-vac across PL11-6 and PL11-12? You have an open wire or bad terminal on either the BLACK or WHITE wire between the variable speed furnace control and the inducer motor.

  • Page 30: Status Code 43 - Low-Heat Pressure Switch Open While High-Heat Pressure Switch Is Closed

    STEP ACTION GO TO Is inducer blower wheel okay? If possible, replace inducer wheel. Otherwise replace inducer motor assembly. Is there any frost build-up on combustion-air inlet? The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe.

  • Page 31: Status Code 45 - Control Circuitry Lockout

    STEP ACTION GO TO Is 24-vac across ORANGE wire on the low heat pressure switch LPS and C -24V on variable speed furnace control? Is 24-vac across connector terminal PL1-4 and C -24V on variable speed furnace control? Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. You have an open circuit between the low heat pressure switch LPS and the variable speed furnace control.

  • Page 32: Appendix A - Board Layout & Wiring Schematic

    APPENDIX A BOARD LAYOUT AND WIRING SCHEMATICS COMMUNICATION CONTINUOUS FAN OUTDOOR SW4 SETUP CONNECTOR (CF) AIRFLOW AIR TEMP SWITCHES SETUP SWITCHES CONNECTOR MODEL PLUG CONNECTOR SW1 SETUP SWITCHES AND BLOWER OFF- DELAY AIR CONDITIONING (A/C) AIRFLOW SETUP SWITCHES HUMIDIFIER TERMINAL (24-VAC 0.5 AMP MAX.
  • Page 33 Fig. 2 – Schematic for 355MAV and 355AAV with ECM 2.5 Blower Motor - 33 -...
  • Page 34 Fig. 3 – Schematic for 355AAV with ECM 3.0 Blower Motor - 34 -...
  • Page 35 Fig. 4 – Schematic for 355BAV with ECM 2.5 Blower Motor - 35 -...

  • Page 36: Appendix Becm Blower Motor Description & Operation

    APPENDIX B ECM BLOWER MOTOR DESCRIPTION & OPERATION The G.E. Electronically Commutated Motor (ECM) shown in figure 5 is different than previous generations of variable speed blower motors. This motor has all of the capabilities of previous ECM blower motors but it does not have to be pre-programmed at the factory. Instead the variable speed furnace control programs the ECM blower motor upon application of power to the ECM blower motor via the serial communication link between the variable speed furnace control and the ECM blower motor.

  • Page 37: Appendix Cpressure Check Diagram

    APPENDIX C PRESSURE CHECK DIAGRAM 355MAV & 355AAV PRESSURE SWITCH MAKE/BREAK POINTS HIGH-HEAT PRESSURE SWITCH LOW-HEAT PRESSURE SWITCH UNIT SIZE (BTUH) Make Point Break Point Make Point Break Point 40,000 1.81 in.wc max 1.63 in. wc +/- 0.05 0.75 in. wc max 0.60 in.

  • Page 38: Appendix Dstatic Pressure Reading Location Diagrams

    APPENDIX D STATIC PRESSURE READING LOCATION DIAGRAMS Figure 7 – Upflow Total Static Pressure Reading Locations Figure 8 – Downflow Total Static Pressure Reading Locations - 38 -...
  • Page 39 Figure 9 – Horizontal Right Total Static Pressure Reading Locations Tools Needed: Pitot Tube Incline Manometer/Magnahelic Example 1: Return ESP after Filter 0.20 in.w.c. Supply ESP before Coil 0.40 in.w.c. ------------------------------------------------------ Total ESP 0.60 in.w.c. Example 2: Return ESP before Filter 0.10 in.w.c.

  • Page 40: Appendix Equick Reference Information

    Typical Reading: 4 to 6 microamps in high heat Hot Surface Ignitor Reading: 355MAV – Ohm reading of new HSI @ 70°F: 40 to 90 ohms (resistance will go up with HSI life and exceed the new HSI resistance over time).

  • Page 41: Appendix Ffurnace Staging Algorithm

    APPENDIX F FURNACE STAGING ALGORITHM On initial thermostat call for heat after power-up, furnace staging algorithm will provide 16 minutes of low heat provided setup switch SW1-2 is off. If call for heat still exists after operating for 16 minutes in low heat, furnace switches to high heat until the thermostat is satisfied. During subsequent calls for heat: Low heat run time is calculated based on previous heating cycle.
  • Page 42 A02281 - 42 -...
  • Page 43 SERVICE TRAINING Packaged Service Training programs are an excellent way to increase your knowledge of the equipment discussed in this manual, including: • Unit Familiarization • Maintenance • Installation Overview • Operating Sequence A large selection of product, theory, and skills programs is available, using popular video-based formats and materials.
  • Page 44 - 44 - Replaces: SM05-5 Form: SM05-07 6-08...

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