Bryant 333B-AV-036060-AA-JA Troubleshooting Manual page 23

STEP
Return SW-1 and SW-2 to original desired settings and go to page number indi-
10.
cated in Index for CLEANUP AND START-UP INSTRUCTIONS.
Consider this like a status code 13 and go to page number indicated in Index
11.
for Status Code 13.
Do you have 24 vac across connector terminal PL1-2 and C
12.
furnace control?
13. Replace 2-stage furnace control.
Do you have 24 vac across connector terminal PL1-3 and C
14.
furnace control?
15. Turn power off.
16. Do you have continuity across limit switch LS?
17. Wait for unit to cool then recheck for continuity across limit switch LS.
18. Do you have continuity across limit switch LS?
19. Replace limit switch.
20. Do you have continuity across flame rollout switch(es) FRS?
21. Can flame rollout switch(es) FRS be reset?
22. Replace flame rollout switch FRS.
Reset flame rollout switch(es) FRS, turn power on, and observe furnace opera-
23.
tion for (2) 15 minute cycles.
24. Does flame rollout switch(es) FRS trip again?
25. Does a different status code flash?
You have inadequate combustion-air supply. This may be caused by:
• Poor burner, manifold, or orifice alignment.
26. • Blocked heat exchanger.
• Leak in heat exchanger.
• Furnace installed in a negative pressure area.
27. Fix problem
You have an open RED wire or bad terminal in limit circuit. Repair wire or re-
28.
place harness.
Does furnace have proper limit switch, limit shield, and blower shelf (if used)? If
29.
so, are limit switch, limit shield, and heat exchangers properly aligned?
30. Does furnace have a variable-speed ICM blower motor?
STEP TERMINAL CONNECTIONS*
HUM
31.
WHITE (+)
PL9-2
32.
WHITE (+)
STEP
Make sure blower off delay is set to 135 sec or more, then disconnect W/W1
33.
thermostat lead from 2-stage furnace control.
Does blower motor change speed 90 sec after W/W1 thermostat lead was dis-
34.
connected from 2-stage furnace control.
35. Replace ICM blower motor.
36. Jumper R and W/W1 thermostat terminals.
37. Does status code 33 occur during low fire?
38. Clean or replace filter if necessary, then recycle furnace after limit resets.
39. Observe furnace operation for 25 minutes or until status code 33 starts flashing.
40. Does status code 33 occur?
Is furnace considerably overfired (10% or more)? Clock input rate. Do not use
41.
manifold pressure method unless using propane.
Ensure gas inlet pressure and burner orifices (natural or propane) are correct.
42. Then adjust gas valve to proper rate per Installation, Start-Up, and Operating
Instructions. If it cannot be adjusted to proper rate, replace gas valve.
43. Is temperature rise within rise range?
44. Does installation have a bypass humidifier or zoning system bypass?
With blower door in place, record temperature rise across return-air duct before
45.
and after bypass.
46. Is temperature rise from bypass greater than 15°F?
47. The bypass is oversized. Adjust damper or replace with properly sized bypass.
48. Does installation have modulating zone dampers?
Disable modulating zone damper system with all dampers in open position ex-
49. cept bypass damper. If installation is equipped with a bypass damper, it should
be in closed position.
Turn power off and disconnect jumper from R thermostat terminal. Turn power
50. back on and reconnect jumper to R thermostat terminal. Observe for 15 minutes
with blower door in place.
51. Does status code 33 flash?
ACTION
VOLTAGE
C -24V
OM
to 24 vac
(-)
PL9-3
to 24 vac
BLACK (-)
ACTION
-24V on 2-stage
OM
-24V on 2-stage
OM
If voltages are correct, go to Step 32. If not, replace 2-stage
furnace control.
If voltages are correct, go to Step 33. If not, repair or replace
ICM blower harness.
—23—
YES NO GO TO
— — INDEX
— — INDEX
14 13 —
— — 10
13 15 —
— — 16
20 17 —
— — 18
20 19 —
— — 10
28 21 —
23 22 —
— — 10
— — 24
26 25 —
9 10 —
— — 27
— — 10
— — 10
30 27 —
31 37 —
ACTION
YES NO GO TO
— — 34
36 35 —
— — 10
— — 37
38 59 —
— — 39
— — 40
41 10 —
42 43 —
— — 10
56 44 —
45 48 —
— — 46
47 48 —
— — 10
49 53 —
— — 50
— — 51
53 52 —