Section 17. Troubleshooting - Trane A5HP4 Installation And Operation Manual

Section 17. Troubleshooting

Wait 3 minutes and
check contactor
coil again
YES
If applicable, is TDR
input voltage
present
NO
Check ID Low
voltage
transformer
Before starting, insure proper fan motor
operation and both indoor and outdoor
coils are clean and clear of ice.
Measure sub-cooling at
the outdoor unit.
Is subcooling greater
than 8°?
NO
Verify system charge
88-A5HP4001-1A-EN
Compressor fails to start
Contactor check
Is contactor
YES
engergized?
(contacts closed)
NO
Check for 24 volts AC
across contactor coil
Is voltage
YES
NO
present at
contactor coil?
NO
Check control
transformer and
control fuse
Is the control
YES
transformer
and fuse good?
NO
Repair or replace
transformer or fuse.
Investigate cause for
failure (possible short in
field wiring)
Is outdoor
YES ambient above
55 °F?
YES
Stop. Outdoor
ambient is too
warm for this
test
Go To: Compressor won't run
Replace contactor
Jumper R to Y low
voltage terminals
at thermostat sub
base.
Repair or replace
connecting wiring
Troubleshooting Outdoor TXV / Heating Mode
Measure superheat on suction
line at TXV sensing bulb.
NO
Is superheat over 6°F and
under 20°F?
NO
Remove sensing bulb from the
suction line. Observe liquid
pressure and suction pressure while
holding the bulb in bare hand for
one minute.
Does Liquid pressure decrease and
suction pressure increase?
Does the
Replace the room
YES
contactor
thermostat
energize?
NO
YES
YES TXV is OK
Replace the
NO
TXV
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