Troubleshooting guide, Symptom and probable cause, Probable remedy – Carrier 38ED User Manual
Page 12: Compressor runs but cooling is insufficient, High suction pressure, Compressor shuts off, Will not restart, Contactor closed or closes then opens
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TROUBLESHOOTING GUIDE
SYMPTOM AND
PROBABLE CAUSE
PROBABLE REMEDY
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
system, system restricted
n
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.
3.
Condenser coil blocked See Maintenance, Coil
Cleaning Check airflow clearance (Fig 1)
Review Refrigerant Charging procedures, purge
system, replace filter drier, check refrigerant
control.
Review Installation, Step 4; replace capacitor.
1. Tighten fan hub setscrews, see Condenser Fan
Motor Removal.
2 Check unit wiring. Check motor bearings Re
place motor.
COMPRESSOR RUNS BUT COOLING
IS INSUFFICIENT
1. Low refrigerant charge.
2 Dirty filters, partially restrict airflow (evaporator
coil may be partially iced)
High Suction Pressure
1 Defective compressor valves (accompanied by
low head pressure)
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
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 See Compressor Runs But Cooling Is Insufficient
above regarding filters, ductwork, etc
2 Check refrigerant flow device, be sure correct
AccuRater™ or TXV 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 II circuit faulty
Check control circuit components and wiring.
Refer to unit label diagram, check all conditions.
Refer to Standard Service Techniques Manual,
Chapter 2, Electrical.
Check main power supply wiring Refer to Elec
trical Data table and label diagram Substitute
Time Guard II with a replacement to verify its
operation 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
Form38ED-1SI New
Printed in U.S.A
1-83
PC 101
Catalog No. 563-822