Carrier 38VH - Manual (Page 12)

TROUBLESHOOTING GUIDE
SYMPTOM AND
PROBABLE CAUSE
COMPRESSOR SHUTS OFF, FAN OVERLOAD
OR HIGH PRESSURE SWITCH CUT OUT, OR
INTERNAL PRESSURE RELIEF OPENS
Condenser Fan On
1 Condenser air restricted or recirculating
2 Refrigerant overcharge, noncondensables in
system system restricted
3 Improper line voltage, loose electrical connec­
tions, faulty run capacitor
Condenser Fan Off
1 Fan slipping on shaft, fan motor bearing stuck,
fan motor defective.
2 Loose electrical connections Fan motor over­
load open
COMPRESSOR RUNS BUT COOLING
IS INSUFFICIENT
1 Low refrigerant charge.
2 Dirty filters, partially restricts airflow (evaporator
coil may be partially iced).
High Suction Pressure
1. Defective compressor valves (accompanied by
low head pressure)
PROBABLE REMEDY
1 Condenser coil blocked Maintenance, Coil
Cleaning Check airflow clearance (Fig 1)
2 Review Refrigerant Charging procedures, purge
system, replace filter-drier, check refrigerant
control
3 Review Installation, Step 3, replace capacitor
1 Tighten fan hub setscrews, see Condenser Fan
Motor Removal
2 Check unit wiring Check motor bearings Re­
place motor
COMPRESSOR SHUTS OFF FROM
LOW-PRESSURE SWITCH CUTOUT
Evaporator Fan Runs
1 Low refrigerant charge or restricted evaporator
air
2 Restricted refrigerant flow.
Evaporator Fan Stopped
1 Evaporator fan-motor defective or inoperative.
1. Check Refrigerant Charging procedures
2 Check evaporator air system for dirty filters,
obstruction in ductwork, improper damper
settings. Refer to coil, fan coil or furnace
instructions as applicable.
1. Perform Compressor Replacement procedure.
Recheck system charge.
1. See Compressor Runs But Cooling Is Insufficient
above regarding filters, ductwork, etc.
2 Check refrigerant flow device, be sure correct
AccuRater™ orTXV is used.
1. Check furnace or fan instructions regarding de­
fective fan relay, belt adjustment, condition of
motor bearings and overloads, check and tighten
electrical connections, check power supply.
COMPRESSOR SHUTS OFF,
WILL NOT RESTART
Contactor Open
1 Burned out transformer, open thermostat circuit,
faulty control relay, open overload
Contactor Closed or Closes Then Opens
1 Compressor power is out, compressor motor is
burned out or internal overloads are open. Time
Guard® Circuit faulty
Check control circuit components and wiring
Refer to unit label diagram, check all conditions
Refer to Standard System Techniques Manual,
Chapter 2, Electrical
\
Check main power supply wiring Refer to Elec­
trical Data table and label diagram Substitute
Time Guard with a replacement to verify its oper­
ation Refer to Standard Service Techniques
Manual, Chapter 2, Electrical
For replacement items use Carrier Specified Parts.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
Tab 3a 2a
Form 38VH-2SI Supersedes 38VFI-1 SI Printed in USA 3-80 PC 101 Catalog No. 533-830