Trane 4TWR6 Series - Section 17. Troubleshooting

20 18-AC104D1-1G-EN
Section 17. Troubleshooting
Is contactor
energized?
(contacts closed)
Is voltage
present at
contactor coil?
Replace contactor
YES
NO
NO
Check for 24 volts AC
across contactor coil
Check control
transformer and
control fuse
Is the control
transformer
and fuse good?
NO
YES
Repair or replace
transformer or fuse.
Investigate cause for
failure (possible short in
field wiring)
Jumper R to Y low
voltage terminals
at thermostat sub
base.
Does the
contactor
energize?
NO
Repair or replace
connecting wiring
YES
Go To: Compressor won’t run
Replace the room
thermostat
YES
Compressor fails to start
Contactor check