Trane A4AC3018A1000A Installer's Manual page 25

15.2 Troubleshooting
Compressor fails to start
Contactor check
Is contactor
energized?
(contacts closed)
NO
Check for 24 volts AC
across contactor coil
Is voltage
present at
contactor coil?
NO
Check control
transformer and
control fuse
Is the control
transformer
and fuse good?
NO
Repair or replace
transformer or fuse.
Investigate cause for
failure (possible short in
field wiring)
Single Pole Contactor (MS)*
OUT
HIGH
VOLTAGE
IN
*Refer to Wiring Diagram to determine if a single pole or double pole contactor is used.
88-A4AC3001-1C-EN
TROUBLESHOOTING
YES
Go To: Compressor won't run
YES
Replace contactor
Jumper R to Y low
YES
voltage terminals
at thermostat sub
T2 T1
L2 L1
Does the
contactor
energize?
base.
NO
Repair or replace
connecting wiring
Double Pole Contactor (MS)*
T2
Contactor Coil
24 VAC
L2
Replace the room
YES
thermostat
T1
OUT
HIGH
VOLTAGE
L1
IN
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