5188235-YIM-E-0518
60
Johnson Controls Ducted Systems
Gas Heat Troubleshooting Guide
Before beginning symptomatic troubleshooting activities read
the flash code LEDs on the unit control board (UCB) and the
ignition control board (ICB). Fault codes have a quick sequence
of flashes indicating the flash code number followed by a pause
with the LED off. The ICB flash codes are repeated until the
fault is cleared. The ICB monitors itself, the centrifugal switch,
lockout due to > 16 pilot flame losses, primary limit, roll-out and
a flame present when the ICB expects no flame.
With power applied to the unit, if the LED on the ICB is flashing
the heartbeat and the furnace will not operate, then proceed to
the symptomatic troubleshooting section. If the ICB LED is not
flashing, then perform the ICB troubleshooting procedures. If the
ICB has a flash code other than the heartbeat, then determine
the flash code and locate its troubleshooting procedures in the
flash code troubleshooting section. Refer to Table 30 for flash
code identification and component causing fault.
Flash Code Troubleshooting
Power to the unit should be interrupted during the
troubleshooting of individual components unless otherwise
Table 28: ZE060 (5.0 Ton) Operating Pressures
Air Flow
Indoor Db/Wb
Indoor
DB/WB
Outdoor
DB
Suction
Pressure
Suction
Temp.
Liquid
Pressure
Liquid
Temp.
Delta T
Db
Entering
Evap Db
Leaving
Evap Db
Compressor
Amps
300 Cfm/Ton
80/62
75
123
52
283
77
-30
80
50
14
85
126
53
329
85
-29
80
51
16
95
130
55
381
94
-27
80
53
19
300 Cfm/Ton
80/67
75
135
58
289
79
-24
80
56
14
85
138
58
335
86
-24
80
56
17
95
143
60
387
95
-22
80
58
19
300 Cfm/Ton
80/72
75
147
64
294
80
-19
80
61
15
85
150
64
340
88
-19
80
61
17
95
153
66
392
95
-18
80
62
19
300 Cfm/Ton
75/63
75
124
54
283
76
-24
75
51
14
85
128
55
329
84
-23
75
52
16
95
132
56
382
94
-22
75
53
19
400 Cfm/Ton
80/62
75
130
56
285
78
-26
80
54
14
85
133
57
331
86
-25
80
55
16
95
139
59
382
95
-24
80
56
19
400 Cfm/Ton
80/67
75
141
60
292
79
-21
80
59
15
85
144
61
339
87
-20
80
60
17
95
147
62
390
95
-20
80
60
19
400 Cfm/Ton
80/72
75
152
67
297
80
-16
80
64
15
85
156
67
342
88
-16
80
64
17
95
160
67
396
96
-15
80
65
20
400 Cfm/Ton
75/63
75
132
56
287
77
-20
75
55
14
85
134
57
334
85
-20
75
55
17
95
138
58
386
94
-19
75
56
19
Troubleshooting of components may require opening
the electrical control box with the power connected to
the unit.
Use extreme care when working with live
circuits!
Check the unit nameplate for the correct line
voltage and set the voltmeter to the correct range before
making any connections with line terminals.
When not necessary, shut off all electric power to the
unit prior to any of the following maintenance
procedures so as to prevent personal injury.
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation, which could cause injury to person
and/or damage unit components. Verify proper
operation after servicing.
The furnace may shut down on a high temperature
condition during the procedure. If this occurs, the UCB
energize the supply air blower motor until the high
temperature limit has reset. Caution should be used at
all times as the supply air blower may energize
regardless of the room thermostat fan switch position.
