Carrier 38AK007 - Manual (Page 8)

TROUBLESHOOTING GUIDE
COMPRESSOR DOES NOT RUN
Contactor Open
Power off — restore power.
Fuses blown — replace with correct fuses after finding cause
and correcting.
Transformer dead —
replace transformer if primary wind­
ings are receiving power.
Thermostat circuit open —
check thermostat setting.
Low-pressure switch open — check for refrigerant under­
charge or obstruction of indoor airflow.
High-pressure switch open —
check for refrigerant over­
charge or obstruction of outdoor airflow.
Connections loose —
tighten all connections.
Compressor motor thermostat open — check for excessive
motor temperature.
Contactor Closed
Compressor leads loose — check connections.
Single phasing — replace blown fuse.
COMPRESSOR CYCLES ON
HIGH-PRESSURE SWITCH
Condenser Fan On
High-pressure switch faulty — replace switch.
Airflow restricted — remove obstruction.
Air recirculating — clear airflow area.
Noncondensables in system — purge and recharge as re­
quired.
Refrigerant overcharge —
purge as required.
Refrigerant system restrictions — check or replace filter
drier, expansion valve, etc.
Condenser Fan Off
Fan slips on shaft — tighten fan hub setscrews.
Motor not running — check power and capacitor.
Motor bearings stuck — replace bearings.
Motor overload open — check overload rating. Check for
fan blade obstruction.
Motor burned out — replace motor.
COMPRESSOR CYCLES ON
LOW-PRESSURE SWITCH
Evaporator Air Fan Running
Filter drier plugged — replace filter drier.
Expansion valve power head defective — replace power
head.
Low refrigerant charge —
add charge. Check low-pressure
switch setting.
Airflow Restricted
Evaporator coil iced up — check refrigerant charge.
Evaporator coil dirty — clean coil fins.
Indoor air filter dirty — clean or replace filters.
Indoor air dampers closed — check damper operation and
position.
Evaporator Air Fan Stopped
Electrical connections loose — tighten all connections.
Fan relay defective — replace relay.
Motor overload open — check power supply.
Motor defective — replace motor.
Fan belt broken or slipping — replace or tighten belt.
COMPRESSOR RUNS BUT
COOLING INSUFFICIENT
Suction Pressure Low
Refrigerant charge low — check charge.
Head pressure low — check refrigerant charge.
Indoor-air filters dirty — clean or replace filters.
Expansion valve power head defective — replace power
head.
Evaporator coil partially iced —
check low-pressure
setting.
Evaporator airflow restricted —
remove obstruction.
Suction Pressure High
Heat load excessive — check for open doors or windows.
Copyright 1992 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book|1 |4 PC 111 Catalog No 533-809 Printed in U S A Form 38AK-2SI Pg 8 6-92 Replaces: New
Tab 3a 2a