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.
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