Advanced 90% Furnace. Troubleshooting

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Dina Price
5 years ago
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1 Advanced 90% Furnace Troubleshooting

2 Contact information Instructors: Don Reynolds Doug McGee Factory Tech Support

3 We Have Come a Long Way

4 So, Bubba you going to the training class tonight No, I m to busy with all these service calls to go Or I ve been doing this for thirty years and don t need to go to training. Let s sneak a peek at some of Bubba s installs

5 I m too busy installing a vent pipe tonight

6 I ve be doing this for 30 years, I don t need no training

7 Let s look at what kind of equipment Bubba has at his house

8 Useful Tools: dex.jsp

9 Test Data Sheet

10 Agenda: First Steps In Troubleshooting Two Stage Hybrid Models Two Stage Multi Speed ECM Motor Models Two Stage Variable Speed Models Limit Switch Troubleshooting Pressure Switch Troubleshooting Inducer Motor Troubleshooting

11 First Steps in Troubleshooting The task of troubleshooting can be divided into three basic elements Diagnosis Isolation Correction In other words, defining, locating, and fixing the fault.

12 First Steps In Troubleshooting When checking Voltages always check under a load otherwise a voltage drop will not be detected When checking Inlet Gas Pressure always check with the unit firing. When checking Pressure switch vacuum allow the unit to run for several minutes Never assume anything-verify with your meters

13 You mean I have to Check Gas Pressure, I thought they were preset at The Factory Part Number 0151K00000S.

14 First Steps In Troubleshooting- Voltage Checks

15 Using Schematics To Aid In Troubleshooting

16 When checking voltage, always check across the circuit (hot conductor wire to neutral wire) checking voltage by using the ground or ground wire is not advised Pitfalls of Checking voltage to Ground 120 Ground

17 Verifying Ground (Circuit Boards)

18 Checking Flame Rod Integrity To check a flame rod for possible problems, use a meter which is capable of checking in the micro-amp range. METER IF YOU YOU GET ARE A LOOKING READING FOR REGARDLESS AN INFINITY OF THE VALUE REMOVE READING THE FLAME SENSOR AND EXAMINE MORE CLOSELY MODULE LOOK FOR GLAZING, CRACKS, CARBON TRACKING, MOISTURE AND LOOSE CONNECTIONS Deg.F. GROUND CERAMIC ISOLATOR APPLIANCE BURNER or BRACKET PILOT OR BURNER FLAME KANTHAL ROD

20 Fault Code Recall

21 *MH & DM96HS Model Furnaces Hybrid Furnaces Light On High Stage

22 Front Cover Pressure Switch H models

24 Normal Sequence of Operation Models come from the factory set for single stage thermostat operation- 2 nd. stage set to auto These models Call for heat 1 st Stage on start up Power is supplied to the ICM and a red led shows Board runs a self checking polarity and gas valve Control enters standby mode with a slow green flash Thermostat close R to W1 The Amber led will slow flash for normal The ICM checks limits for closed Checks the low fire pressure switch for open

25 Two Stage Multi Speed Wiring

26 CODES:*Multi Speed ECM Furnaces

27 Fault Codes Two Stage Multi Speed ECM

28 Checking Gas Valve For Voltage Check voltage at the Circuit Board Pin 7 and Pin 8 for 24 volts

29 Limit Switch Circuit

32 Checking Micro-Amp Signal Putting a DC micro amp meter in series with the flame sensor Putting a DC volt meter across the solder pads in the flame current section on the control board 1 DC volt= 1 micro-amp

34 Troubleshooting Multi Speed ECM Motors

35 Troubleshooting Multi Speed ECM Motors

39 Normal Sequence of Operation On power up the ICM preforms internal checks and display shows 88 ICM checks safety circuits and display turns to ON and awaits a call for heat.

40 FIELD TEST MODE- Testing Gas Pressure -Can be used to bring the furnace up to high fire for testing, setting gas pressure -Using Fault Recall & Learn buttons, press from 1-5 seconds and release -Display will flash FT -Input will go to High Fire for 5 mins and display FT without flashing

41 Learn Button Fault Recall Button

42 Memory Cards

44 Checking Gas Valve For Voltage Check voltage at the Circuit Board Pins 13 and Pin 14 for 24 volts

45 Fault Codes Each code flash has a reference it the on the trouble shooting chart portion of the service manual or in the equipment door Each code will give a fault description A list of things to check and caution notes Always reference the manual for more detailed information

46 Fault code retrieval Push and hold the last error button 1-5 sec The LED will flash up to 5 stored codes most recent first with a 2sec pause between codes If none are present you will see two green flashes Hold for 10sec to clear the codes

47 Fault codes:

48 Fault codes Each code flash has a reference it the on the trouble shooting chart portion of the service manual or in the equipment door Each code will give a fault description A list of things to check and caution notes Always reference the manual for more detailed information

49 2 Stage Variable Speed Furnace Fault Codes

51 Think Real Hard!!!!!!!!!!!!!!!!!!!! Q: A pressure switch stuck open fault code means? A. Venting Issues B. Termination Issues C. Inducer Motor Issues D. Pressure Switch Hoses E. Defective Pressure Switch

52 Troubleshooting Pressure Switches

54 2 Speed Inducer Wiring

57 Troubleshooting Inducer Motors

61 Troubleshooting ECM Motors

62 Power Requirements 120v Power Leads Transducer ¾ and 1HP models

64 Troubleshooting ECM Motors

65 Troubleshooting ECM Motors

66 Troubleshooting ECM Motors

67 Troubleshooting ECM Motors

68 Troubleshooting ECM Motors

70 Questions?

Troubleshooting Manual

Troubleshooting Manual NOTICE: DO NOT DISCARD THIS MANUAL Models: LEGACY42-IFT PHOENIX42-IFT 1 TABLE OF CONTENTS A. Normal Operation...3 B. Wiring Diagram...4 C. Troubleshooting IntelliFire Touch...5 D.