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L. TROUBLESHOOTING
TROUBLESHOOTING CHART — WHAT TO CHECK
SYSTEM FAULTS
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
P - Primary Causes
HEAT PUMP SYSTEMS
Thermostat
R
24 VAC HOT
G
FAN
24 VAC
B
Common
O
SOV
COOL/HEAT
Y
1st STAGE
HEATING
W
2nd STAGE
18-BC56D1-5
P
P
P
S
P
P
P
P
P
P
P
P
S
P
P
P
S
S - Secondary Causes
TYPICAL FIELD HOOK-UP DIAGRAMS
Indoor
Outdoor
Unit
Unit
R
R
G
B/C
B
O
Y
X2
W
Black
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.
Installer's Guide
P
P
S
P
S
P
P
S
P
S
P
P
S
P
P
P
P
S
P
S
S
P
S
P
S
P
S
S
S
P
P
Thermostat
R
24 VAC HOT
G
FAN
24 VAC
B
Common
COOLING
Y
HEAT
W
S
P
S
S
S
S
S
S
S
S
P
S
P
S
S
S
P
S
S
S
P
S
S
S
S
AC SYSTEMS
Indoor
Outdoor
Unit
Unit
R
G
B/C
W
B
Y
5
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