18-BC56D1-5
5
Installer’s Guide
REFRIGERANT CIRCUIT
Liquid Pressure Too High
Liquid Pressure Too Low
Suction Pressure Too High
Suction Pressure Too Low
Liquid Refrig. Floodback TXV System
I.D. Coil Frosting
Compressor Runs Inadequate or No Cooling
ELECTRICAL
Compressor & O.D. Fan Do Not Start
Compressor Will Not Start But O.D. Fan Runs
O.D. Fan Won’t Start
Compressor Hums But Won’t Start
Compressor Cycles on IOL
I.D. Blower Won’t Start
SYSTEM FAULTS
P - Primary Causes S - Secondary Causes
P
P
P
S
S
P
S
S
S
S
S
P
S
S
S
P
P
P
S
S
S
S
S
S
S
P
P
P
S
P
P
S
S
S
P
P
P
P
P
P
P
P
P
P
S
S
S
S
P
P
P
P
P
S
S
P
S
P
S
S
S
S
S
S
S
P
P
P
P
P
S
P
P
POWER SUPPLY
HIGH VOLTAGE WIRING
COMPR. IOL
RUN CAPACITOR
START CAPACITOR
START RELAY
CONTACTOR CONTACTS
LOW VOLTAGE WIRING
CONTROL TRANSFORMER
CONTACTOR COIL
LOW VOLTAGE FUSE
STUCK COMPRESSOR
INEFFICI
ENT COMPRESSOR
REFRIGERANT U
NDERCHARGE
REFRIGERANT OVERCHA
RGE
EXCESS
IVE EVAP. LOAD
NONCON
DENSABLES
RESTRICTED O.D. AIRFLOW
O.D. AIR RECIRCULATION
TXV STUCK OPEN
SUPERHEAT
RESTRICTED I.D. AIRFLOW
REF. CIRCUIT RESTRICTIONS
O.D. FAN SPEED
SWITCH
TROUBLESHOOTING CHART — WHAT TO CHECK
TYPICAL FIELD HOOK-UP DIAGRAMS
Notes:
1. Be sure power supply agrees with equipment nameplate.
2. Power wiring and grounding of equipment must comply with local codes.
3. Low voltage wiring to be No. 18 AWG minimum conductor.
L. TROUBLESHOOTING
HEAT PUMP SYSTEMS
R
G
W
R
B
O
Y
X2
R
G
B
B/C
O
Y
W
24 VAC HOT
FAN
24 VAC
Common
SOV
COOL/HEAT
1st STAGE
HEATING
2nd STAGE
Thermostat
Outdoor
Unit
Indoor
Unit
Black
AC SYSTEMS
B
B/C
Indoor
Unit
R
G
W
B
Y
R
G
Y
W
24 VAC HOT
FAN
24 VAC
Common
COOLING
HEAT
Thermostat
Outdoor
Unit
