10.3 Troubleshooting Table
SYSTEM FAULTS
REFRIGERANT CIRCUIT
Head Pressure Too High
Head Pressure Too Low
Suction Pressure Too High
Suction Pressure Too Low
Liquid Refrig. Floodback
(TXV)
I.D. Coil Frosting
Compressor Runs Inadequate
or
No Cooling/Heating
ELECTRICAL
DEFROST
Compressor & O.D. Fan
Won’t Start
Compressor Will Not Start
But O.D. Fan Runs
O.D. Fan Won’t Start
Compressor Hums But Won’t
Start
I.D. Blower Won’t Start
Unit Won’t Initiate Defrost
Defrost Terminates on Time
Unit Icing Up
C
H
C
H
C
H
C
H
C
H
C
H
C
H
S
S
S
S
S
S
P
P
P
P
P
P
P
P
P
P
S
S
S
S
S
S
S
S
S
S
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
S
S
S
S
P
P
S
S
P
P
P
P
P
P
S
S
S
S
S
S
S
S
S
S
P
P
S
S
P
P
P
P
P
S
S
S
S
S
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
S
S
S
S
S
S
S
S
S
S
S
S
S
P
S
S
S
S
S
S
S
P
P
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
S S
S S
S
P
P
P
P
P
S S
S
S
S
S
S
S
C- Cooling H - Heating P - Primary Causes S - Secondary Causes
WHAT TO CHECK MODE
POWER SUPPLY
HIGH VOLTAGE WIRING
I.D. CONTROL DEF.
COMPRESSR CAPACITOR
O.D. FAN CAPACITOR
I.D. BLOWER CAPACITOR
LOW VOLTAGE WIRING
CONTACTOR CONTACTS
CONTROL TRANSFORMER
THERMOSTAT
CONTACTOR COIL
LOW VOLTAGE FUSE
STUCK COMPRESSOR
INEFFICIENT COMP.
REF. UNDERCHARGE
REF. OVERCHARGE
EXCESSIVE EVAP. LOAD
NONCONDENSABLES
RES. O.D. AIRFLOW
TXV STUCK OPEN
SUPERHEAT
RES. I.D. AIRFLOW
REF. CIR. RESTRICTIONG
SOV LEAKING
SOV COIL DEFECTIVE
CHECK VALVE LEAKING
LPC SENSOR DEF.
DEFROST CONTROL DEF.
T4 TEMP. SENSOR DEF.
T3 TEMP. SENSOR DEF.
HPC/HGS SENSOR DEF.
O.D. AIR RECIRCULATION
23
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