Bosch BGH96M080C4B - Page 54

54
|
Installation Instructions
Bosch 96% AFUE Condensing Gas Furnace - BTC 770503101 J (06.2023)
Symptoms of
Abnormal
Operation
Fault
Code
Fault Description(s) Possible Reason Corrective Action Cautions And Notes
Furnace fails
to operate
E7
E8
— Lockout due to
failed ignition
— Lockout due to
too many flame
dropouts
— The gas valve switched off
— Iginitor failure
— Orifices are blocked/clogged
— Flame sensor dirty or broken
— Furnace improperly grounded
— Manifold gas pressure does not
meet the requirement
— Inlet gas pressure does not meet
the requirement
1. Turn the gas valve switch to “On"
2. Replace ignitor
3. Remove the blockage
4. Clean with steel wool.or replace the
flame sensor.
5. Properly ground the wire
6. Adjust the gas valve. Replace the gas
valve.
7. Check incoming gas supply quality.
Adjust the inlet gas pressure to meet
requirement on nameplate.
— Turn power OFF prior to repair.
Furnace fails
to operate
PR
— Incorrect line
voltage polarity
— Wrong L1/L2 connection 1. Correct the wire connection — Turn power OFF prior to repair.
Furnace fails
to operate
BE — Control failure — Control module failure 1. Replace control module — Turn power OFF prior to repair.
Abnormal
Thermostat
Signals
nL
— Abnormal T-stat
signals
— Thermostat wiring issue
— Thermostat failure
1. Correct the wire connection
2. Replace thermostat
―
Abnormal
furnace
operation
FL
— Low flame sense
current
— Flame sensor is coated/oxidized
— Flame sensor is incorrectly
positioned in the burner flame.
— Lazy burner flame due to
improper gas pressure or
combustion air.
1. Clean/sand flame sensor with steel
wool.
2. Inspect for proper sensor alignment.
3. Compare current gas pressure to
rating plate info. Adjust as needed.
— Turn power OFF prior to repair.
— Clean flame sensor with steel
wool.
— See Section 8 for piping
details.
— See rating plate for proper gas
pressure.
Table 28 Troubleshooting Chart
Display Meaning
Operation
Codes
-- Standby mode
H1 1st stage heating
H2 2nd stage heating
C1 1st stage cooling
C2 2nd stage cooling
CF Fan only mode
dF Defrost mode
Table 29 Unit Operation Codes
Online Help Resources
Alternatively, please visit our Service & Support webpage to find FAQs, videos,
service bulletins, and more; www.boschheatingcooling.com/service or use your
cellphone to scan the code below.
Figure 47