Bosch BGH96 - 4, 5, & 11 Flashes (Limit;Rollout Switch Errors)

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Bosch 96% AFUE Gas Furnace Troubleshooting Guide
01.2019 | BTC 770502101 AData subject to change
3.5 4 Flashes (Limit/Rollout Switch Open Less than 5 Mins)
5 Flashes (Limit/Rollout Switch Open More than 15 Mins)
11 Flashes (Limit/Rollout Switch Open from 5 to 15 Mins)
Troubleshooting Chart
Start
Are there any
loose wires or wrong
connections?
Correct wiring
according to
wiring diagram
Yes
No
No
Are the limit
switches working
properly? See
Figure 18 & 19.
Replace the
Limit
Switch
Replace the
(chamber/fan
mounted) Limit
Switch
Is there
blockage in the exhaust
pipe?
Are
(chamber/fan
mounted) limited switches
in right models?
See Table 3
Is the
circulating fan
motor turning on after
30s delay?
Clean/Replace
the filter
Yes
Is there
blockage on the
filter?
“SW2” is used for the fan delay after burner starts.
Replace the
PCB Board
Is the
circulating fan motor
speed correctly set?
See Tables 4
&5
Correct the circulating
fan motor speed or
replace the motor if
necessary.
Check the
airflow duct
for blockage
Yes
No
No
Yes
Yes
Turn off the equipment for 10
minutes to ensure sufficient
cooling off period.Measure the
resistance between two leads
on the limit switches
Verify that the temperature rise is between 40-55°F.
Remove
blockage in
the exhaust
pipe
Yes
Is the
rollout limit switch
showing resistance of
“0”? See Figure
20 & 21.
Yes
Yes
No
Replace the
Rollout
Switch
After
manual reset of the
limit switch(by pressing the
button on switch),is the
error still present
once the system
starts up?
Is the
inducer
working
properly?
Yes
Yes
Replace the
inducer
Yes
No
No
Yes
Is
there power to
the circulating fan motor?
See Figure 7
Replace the
circulating fan
motor
Yes
Replace the
PCB Board
No
No