Bryant 333B-AV-036060-AA-JA, Troubleshooting Manual

Page: 17 / 46

STEP ACTION YES NO GO TO
39.
Does status code 24 begin flashing when high-heat pressure switch HPS is en-
ergized?
40 33 —
40. Turn power off and disconnect PL1 from 2-stage furnace control. — — 41
41. Do you have continuity between BROWN wire and chassis ground? 42 3 —
42.
The BROWN wire to high-heat pressure switch HPS and gas valve GV is short-
ing to ground. Replace or repair it.
— — 11
43.
Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait
until blower stops.
— — 44
44. Jumper R, G, and Y/Y2 thermostat terminals. — — 45
45. Does status code 24 begin flashing when G and Y/Y2 are energized? 72 46 —
46. Does furnace have a variable-speed ICM blower motor. 55 47 —
47.
Reconnect all thermostat leads (except humidifier lead to HUM terminal) to
2-stage furnace control and operate furnace in heating and cooling mode from
thermostat.
— — 48
48. Does status code 24 occur during heating cycle? 49 50 —
49.
You have a defective thermostat or a short circuit in R, W/W1, or W2 wiring be-
tween thermostat, furnace, and outdoor unit. If furnace is twinned, also check
twinning kit relay TKR.
— — 11
50. Does status code 24 occur during cooling cycle? 51 52 —
51.
You have a defective thermostat; short circuit in G, Y1, Y/Y2, or O wiring be-
tween thermostat and outdoor unit; or a short circuit in outdoor unit contactor or
reversing valve (heat pump only).
— — 11
52. Does problem usually occur in cooling mode? 53 54 —
53.
Check outdoor unit contactor. Failure to pull in can cause excessive current
draw on low-voltage circuit. This can be an intermittent problem.
— — 11
54.
Reconnect humidifier and check for excessive current draw. If current draw is
excessive check wiring to humidifier solenoid, diode bridge (if used), and hu-
midifier solenoid.
— — 11
55. Disconnect jumper wire across R, G, and Y/Y2 thermostat terminals. — — 56
56.
Jumper loose end of WHITE wire that is normally connected to HUM quick-
connect terminal on 2-stage furnace control to R thermostat terminal.
— — 57
57. Does status code 24 flash? 58 65 —
58.
Disconnect PL9 from variable-speed ICM blower motor and replace secondary
voltage fuse.
— — 59
59. Does status code 24 flash? 61 60 —
60. Replace ICM blower motor. — — 4
61.
Disconnect PL7 from EZ-SELECT airflow control and replace secondary voltage
fuse.
— — 62
62. Does status code 24 flash? 64 63 —
63. Replace EZ-SELECT airflow control. — — 4
64.
There is a direct short to ground in ICM blower harness. Repair or replace ICM
blower harness then reconnect PL7.
— — 4
65.
Disconnect jumper from WHITE wire that is normally connected to HUM quick-
connect terminal on 2-stage furnace control. Then reconnect WHITE wire back
to HUM quick-connect terminal on 2-stage furnace control.
— — 66
66. Jumper Y1 from EZ-SELECT airflow control to R thermostat terminal. — — 67
67. Does status code 24 flash? 58 68 —
68. Disconnect jumper across Y1 and R. — — 69
69. Jumper O from EZ-SELECT airflow control to R thermostat terminal. — — 70
70. Does status code 24 flash? 58 71 —
71. Reconnect thermostat leads to Y1 and O from EZ-SELECT airflow control. — — 47
72. Does furnace have a variable-speed ICM blower motor? 73 3 —
73.
Disconnect PL4 from 2-stage furnace control and replace secondary voltage
fuse.
— — 74
74. Does status code 24 flash? 3 75 —
75. Reconnect PL4 to 2-stage furnace control. — — 58
76. Does furnace have a variable-speed ICM blower motor? 77 3 —
77.
Reconnect PL1 to 2-stage furnace control, disconnect PL4 from 2-stage furnace
control, replace secondary voltage fuse, and turn power back on.
— — 78
78. Does status code 24 flash? 3 75 —
79. Continue to observe furnace operation for 10 minutes. — — 80
80. Does status code 24 flash after blower comes on? 81 82 —
81. The insulation is loose and has shorted against limit switch. — — 11
82.
Check for loose or torn insulation, because it can cause intermittent occur-
rences of status code 24.
— — 43
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