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Service/Review...Service/Review...
Rule # 1:
Use the KISS Principle!
Service/Review...Service/Review...
Rule # 1:
KeepItSimpleStupid
Start with the BASICS!Start with the BASICS!
Assume nothing, check Assume nothing, check everythingeverything, no , no matter how unrelated it may seem.matter how unrelated it may seem.
Forget everything that’s been done in Forget everything that’s been done in the past service calls.the past service calls.
Check low voltage connections, check Check low voltage connections, check line voltage connections. Check line voltage connections. Check voltages.voltages.
Check pressures, cycle it on the Check pressures, cycle it on the thermostat. Cycle it on the safeties. thermostat. Cycle it on the safeties. Drop out a motor.Drop out a motor.
Start with the BASICSStart with the BASICS!!(con”t)(con”t)
Wiggle wires, jiggle connections Wiggle wires, jiggle connections and look everywhere.and look everywhere.
Ignore your urges, remember that Ignore your urges, remember that the last guy did what you’re the last guy did what you’re considering and look how considering and look how productive that was.productive that was.
What are you looking for? - Won’t What are you looking for? - Won’t know until you find it!know until you find it!
SELF DIAGNOSTIC SELF DIAGNOSTIC FEATUREFEATURE
The IFC tests for internal & external faults The IFC tests for internal & external faults before allowing a heating sequence to begin.before allowing a heating sequence to begin.
The external check includes all safety devices The external check includes all safety devices & pressure switches, making certain that they & pressure switches, making certain that they are in their proper normally open or closed are in their proper normally open or closed position. 24 volt signal leaves HLO to HLI to position. 24 volt signal leaves HLO to HLI to check limits & PS/PS1 for pressure switch.check limits & PS/PS1 for pressure switch.
If a fault is detected the IFC will immediately If a fault is detected the IFC will immediately enter into a fault mode and flash the LED enter into a fault mode and flash the LED according to the fault detected.according to the fault detected.
(Red Book-Page 9)
SELF DIAGNOSTICSELF DIAGNOSTIC
The IFC will remain in the fault mode until the The IFC will remain in the fault mode until the problem is corrected. Once the fault is cleared, problem is corrected. Once the fault is cleared, the IFC will start the heating sequence as long the IFC will start the heating sequence as long as the call for heat still exists.as the call for heat still exists.
The IFC has expanded diagnostic features that The IFC has expanded diagnostic features that monitors the system. If a fault is detected , the monitors the system. If a fault is detected , the IFC will de-energize the gas valve & flash the IFC will de-energize the gas valve & flash the LED.LED.
The control will automatically reset a lock-out The control will automatically reset a lock-out due to loss of flame, see IFC table page 10 due to loss of flame, see IFC table page 10 reset time.reset time.
(Red Book-Page 9)
SELF DIAGNOSTICSELF DIAGNOSTIC
SERVICE CALLSERVICE CALL IMPORTANT:IMPORTANT: Do not remove Do not remove
blower door or turn off power blower door or turn off power before checking flash rate LED. before checking flash rate LED. Sight glass is provided on upflow Sight glass is provided on upflow models in the blower door panel. models in the blower door panel. (Pre W4, series furnaces)(Pre W4, series furnaces)
Note LED flash rate timing.Note LED flash rate timing.
(Red Book-Page 9)
Diagnostic Code LabelDiagnostic Code Label Flashing Slow Flashing Slow one/ secone/ sec Normal, No CallNormal, No Call Flashing Fast Flashing Fast two/sectwo/sec Call for HeatCall for Heat Continuous OnContinuous On Replace ControlReplace Control Continuous OffContinuous Off Check PowerCheck Power 2 Flashes *2 Flashes * External LockoutExternal Lockout 3 Flashes3 Flashes Inducer / Pr. Switch ErrorInducer / Pr. Switch Error 4 Flashes4 Flashes Open Thermal Limit SwitchOpen Thermal Limit Switch 5 Flashes5 Flashes Flame Sensed w/o GV OnFlame Sensed w/o GV On 6 Flashes6 Flashes Ground, Polarity, Low VoltsGround, Polarity, Low Volts 7 Flashes7 Flashes Gas Valve Circuit ErrorGas Valve Circuit Error 8 Flashes8 Flashes Low Flame Sense SignalLow Flame Sense Signal 9 Flashes9 Flashes Open IgniterOpen Igniter
Improper GroundImproper Ground
Low VoltageLow Voltage
Faulty TriacFaulty Triac
More Than 10 Volts Between Neutral and More Than 10 Volts Between Neutral and Ground Ground
Flash Rate 1/4 sec on and 1/4 sec off, with 2 sec Pause Between Groups of Flashes
SELF DIAGNOSTIC SELF DIAGNOSTIC FEATUREFEATURE
CONTINUOUS ON - internal fault, or CONTINUOUS ON - internal fault, or grounded sensor. grounded sensor. Turn power off & on Turn power off & on before replacing, may work OK.before replacing, may work OK.
2 FLASH - System lockout - no flame. See 2 FLASH - System lockout - no flame. See 3 FLASH - Pressure switch error.3 FLASH - Pressure switch error. 4 FLASH - TCO (limit) open.4 FLASH - TCO (limit) open. 5 FLASH - Flame sensed with gas valve de-5 FLASH - Flame sensed with gas valve de-
energized, (stuck open)energized, (stuck open)
(Red Book-Page 9)
1
Fault Diagnostics - 2 Fault Diagnostics - 2 FLASHFLASH
System lockout (loss of flame)System lockout (loss of flame) BAD GROUND BAD GROUND
(power) (power) LOOSE GROUND LOOSE GROUND
(wire or burner)(wire or burner) WRONG GAS WRONG GAS
PRESSUREPRESSURE BAD HOT SURFACE BAD HOT SURFACE
IGNITORIGNITOR DIRTY SENSORDIRTY SENSOR BAD SENSORBAD SENSOR NO GASNO GAS
CHECK ALL CHECK ALL CONNECTIONSCONNECTIONS
SET WITH WATER SET WITH WATER MANOMETERMANOMETER
OHM OUT REPLACE OHM OUT REPLACE IF BADIF BAD
CHECK CHECK amp amp SIGNALSIGNAL
REPL. IF BADREPL. IF BAD GAS SUPPLY, SHUT GAS SUPPLY, SHUT
OFF, GAS VALVEOFF, GAS VALVE
(Red Book-Page 11)
MICROAMP SIGNALMICROAMP SIGNAL
If you are getting call backs w/ two If you are getting call backs w/ two flash and have measured good flash and have measured good amp amp signal check ground wire. signal check ground wire.
MUST BE DIRECT FROM UNIT TO PANEL MUST BE DIRECT FROM UNIT TO PANEL BOX.BOX.
Also check burner closet to flame rod Also check burner closet to flame rod for good clean tight connection.for good clean tight connection.
MICRO AMP METER HOOK UPMICRO AMP METER HOOK UP
(Red Book-Page 25)
HOOK UP METER IN SERIES
LOCKOUT - 2 FLASHLOCKOUT - 2 FLASH
A momentary loss of gas supply, A momentary loss of gas supply, flame blowout, or a shorted or flame blowout, or a shorted or open flame sensor will be sensed open flame sensor will be sensed within .7 seconds during normal within .7 seconds during normal heating cycle.heating cycle.
When a system lockout occurs, When a system lockout occurs, the IFC de-energizes the gas the IFC de-energizes the gas valve, energizes the inducer valve, energizes the inducer motor and indoor blower to heat motor and indoor blower to heat speed. speed.
(Red Book-Page 11)
Flame Sensing - VariablesFlame Sensing - Variables
Remember Ohms Law E=I Remember Ohms Law E=I x Rx R
Watch that resistanceWatch that resistance Too little DC = too badToo little DC = too bad Too much AC = too badToo much AC = too bad Grounded flame sensorGrounded flame sensor Look out for noise!Look out for noise!
Increased Circuit Increased Circuit ResistancesResistances
Burner oxidationBurner oxidation Non-secure burnerNon-secure burner Flame “lift off”Flame “lift off” Loose wire connectionsLoose wire connections Contaminated flame sensorContaminated flame sensor Faulty groundsFaulty grounds No groundsNo grounds Reverse polarityReverse polarity
Fault Diagnostics - 3 Fault Diagnostics - 3 FLASHFLASH
Single StageSingle Stage
Bad vent system - improper draft, Bad vent system - improper draft, flue pipe or chimney blocked or flue pipe or chimney blocked or plugged.plugged.
Bad venter motor or fan dirty.Bad venter motor or fan dirty. Heat exchanger plugged or cracked.Heat exchanger plugged or cracked. 90% units PVC not supported or 90% units PVC not supported or
pitched correctly back towards unit.pitched correctly back towards unit. ?? Maybe a bad pressure switch.???? Maybe a bad pressure switch.?? A draft gauge or incline needed for A draft gauge or incline needed for
testingtesting..
(Red Book-Page 11)
Fault Fault DiagnosticDiagnostic - 3 FLASH - 3 FLASHTwo Stage and Variable SpeedTwo Stage and Variable Speed
Blocked condensate drainBlocked condensate drain 90% - 30 second off to drain condensate90% - 30 second off to drain condensate Inducer starts on hi speed then goes to Inducer starts on hi speed then goes to
lowlow If 2nd stg PS after 3 min delay IFC If 2nd stg PS after 3 min delay IFC
restarts unit and run for 10 min. If 2nd restarts unit and run for 10 min. If 2nd stg PS still dose not close after 10 min stg PS still dose not close after 10 min IFC will start cycle again as long as IFC will start cycle again as long as there is a call for 2nd stage heat at there is a call for 2nd stage heat at thermostat.thermostat.
(Red Book-Page 12)
3 FLASH - cont3 FLASH - cont.. Variable Speed / TUY-R-AVariable Speed / TUY-R-A
If 1st stg PS opens during 1st stg call for If 1st stg PS opens during 1st stg call for heat, gas valve is de-energized and heat, gas valve is de-energized and inducer will go to hi speed for 10 min. If inducer will go to hi speed for 10 min. If PS closes during 10 min the IFC will PS closes during 10 min the IFC will restart ignition sequence. If PS dose not restart ignition sequence. If PS dose not close the inducer will be energized to hi close the inducer will be energized to hi again and continue cycle as long as 1st again and continue cycle as long as 1st stg heat is calling.stg heat is calling.
2nd stg operation is same as page 12.2nd stg operation is same as page 12.
(Red Book-Page 13)
Fault Diagnostic - 4 FLASHFault Diagnostic - 4 FLASH
Thermal Protection Devices Thermal Protection Devices OpenOpen TCO limit, aux.. limit, flame roll out, bad TCO limit, aux.. limit, flame roll out, bad
indoor blower motor, wrong motor indoor blower motor, wrong motor speed, 90% units inducer limit (155’F speed, 90% units inducer limit (155’F open), burner box manual reset limit. open), burner box manual reset limit.
If TCO is open check temperature rise If TCO is open check temperature rise through unit, check specs on unit label. through unit, check specs on unit label.
(Red Book-Page 13)
Fault Diagnostic-5 FLASHFault Diagnostic-5 FLASH
Flame sensed without a call for Flame sensed without a call for heat or when gas valve is de-heat or when gas valve is de-energized. The IFC will energize energized. The IFC will energize indoor blower to run on heating indoor blower to run on heating speed. speed.
The system goes into lockout and The system goes into lockout and will not be reset until this fault is will not be reset until this fault is corrected.corrected.
(Red Book-Page 13)
IFC Quick ReferenceIFC Quick Reference
YOU MUST HAVE:YOU MUST HAVE: SERVICE TIPSSERVICE TIPS Volt/OHM Meter with Volt/OHM Meter with
micro amp scale micro amp scale AA Water ManometerWater Manometer Incline Manometer Incline Manometer
with a 0 - 2” range with a 0 - 2” range Dwyer #1227 goodDwyer #1227 good
Pocket ThermometerPocket Thermometer
(Red Book-Page 20)
IFC requires 1.0IFC requires 1.0A A minimum flame minimum flame signalsignal
80&90% single stage 80&90% single stage 1.8-3.0 1.8-3.0
80&90% two stage 80&90% two stage 1st stg 1.2-1.8 1st stg 1.2-1.8 A A 2nd stg 2.3-3.02nd stg 2.3-3.0A A A good procedure is A good procedure is
to check to check A signal B4 A signal B4 cleaning and aftercleaning and after
Radiant Sense Ignition Radiant Sense Ignition ControlsControls
Radiant sense was used for a short time Radiant sense was used for a short time on TUE Trane units. The control system on TUE Trane units. The control system is no longer used. There are six different is no longer used. There are six different versions how to identify see pages 39-versions how to identify see pages 39-40. 40.
Page 41 shows sensor and correct Page 41 shows sensor and correct position of hot surface ignitor. position of hot surface ignitor.
The rest of the pages are sequence of The rest of the pages are sequence of operation and wiring schematics. Use as operation and wiring schematics. Use as needed.needed.
(Red Book-Pages 39-49)
Troubleshooting Troubleshooting ProceduresProcedures
If the LED on the IFC is on If the LED on the IFC is on continuously, the fault is internal to continuously, the fault is internal to the IFC. To make sure, interrupt line the IFC. To make sure, interrupt line voltage for a few seconds and then voltage for a few seconds and then restore. If internal fault is indicated restore. If internal fault is indicated again, and flame sensor is not again, and flame sensor is not shorted to ground, replace control.shorted to ground, replace control.
Note Note cautioncaution on on five flashfive flash fault. fault.
(Red Book-Page 50)
Troubleshooting Troubleshooting ProceduresProcedures
Flow charts for controls 50A50, 50A51, Flow charts for controls 50A50, 50A51, and 50A52.and 50A52. Page numbers are off by Page numbers are off by two, 49=51, 50=52, 51=53 etc. correct two, 49=51, 50=52, 51=53 etc. correct now.now.
50A50 flame sensor fault (2 flash) what 50A50 flame sensor fault (2 flash) what chart and page do we go to??chart and page do we go to??
Page 55, chart 5a - 5p Page 55, chart 5a - 5p Lets do it.Lets do it. Pages 51 - 64 flow charts.Pages 51 - 64 flow charts.
(Red Book-Page 50)
Service/Review...Service/Review...
Observe...Observe... Ask questions…Ask questions… Observe…Observe… Check Fault Codes...Check Fault Codes... Check equipment / proper Check equipment / proper
sequence of operation, etc...sequence of operation, etc... Proper tools!Proper tools!
Installation/ServiceInstallation/Service(Review)(Review)
Things We Need To Get Better At:Things We Need To Get Better At: Gathering Information from the consumer.Gathering Information from the consumer. Looking beyond the failure in front of us, why Looking beyond the failure in front of us, why
did it fail. Shit does did it fail. Shit does not just happen!not just happen! Running the system long enough to stabilize: Running the system long enough to stabilize:
Checking your temperature rise or subcooling Checking your temperature rise or subcooling and superheat.and superheat.
Remember - Over 50% of the electronic Remember - Over 50% of the electronic controls replaced, did not need to be replacedcontrols replaced, did not need to be replaced..
Sample Service Ticket-
WHAT’S WRONG?
