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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