Carrier 38AF Series, Installation Manual

Page: 13 / 18

13
TROUBLESHOOTING (cont.)
Problem Solution
COMPRESSOR CYCLES ON LOW-
PRESSURE SWITCH (cont.)
Airflow Restricted
1. Coil iced up.
2. Coil dirty.
3. Air filters dirty.
4. Dampers closed.
Indoor-Air Fan Stopped
1. Electrical connections loose.
2. Fan relay defective.
3. Motor overload open.
4. Motor defective.
5. Fan belt broken or slipping.
COMPRESSOR RUNNING BUT COOLING
INSUFFICIENT
Suction pressure low
1. Refrigerant charge low.
2. Head pressure low.
3. Air filters dirty.
4. Expansion valve power head
defective.
5. Indoor coil partially iced.
6. Indoor airflow restricted.
Suction Pressure High
1. Unloaders not functioning.
2. Compressor valve defective.
3. Heat load excessive.
UNIT OPERATES TOOLONG OR
CONTINUOUSLY
1. Low refrigerant charge.
2. Control contacts fused.
3. Air in system.
4. Partially plugged expansion valve
or filter drier.
SYSTEM IS NOISY
1. Piping vibration.
2. Compressor noisy.
COMPRESSOR LOSES OIL
1. Leak in system.
2. Crankcase heaters not energized
during shutdown.
3. Improper interconnecting piping
design.
FROSTED SUCTION LINE
Expansion valve admitting excess refrigerant.
HOT LIQUID LINE
1. Shortage of refrigerant due to leak.
2. Expansion valve opens too wide.
FROSTED LIQUID LINE
1. Restricted filter drier.
2. Liquid line solenoid valve partially
closed.
COMPRESSOR WILL NOT UNLOAD
1. Defective unloader.
2. Defective capacity control solenoid
valve (if used).
3. Miswired capacity control liquid line
solenoid(if used).
4. Weak,broken ,or wrong valve body
spring.
COMPERSSOR WILL NOT LOAD
1. Miswired capacity control liquid line
solenoid (if used).
2. Defective capacity control solenoid
valve (if used).
3. Plugged strainer (high side).
4. Stuck or damaged unloader piston
or piston ring (s)
1. Check refrigerant charge.
2. Clean coil fins.
3. Clean or replace filters.
4. Check damper operation and position.
1. Tighten all connections.
2. Replace relay.
3. Power supply.
4. Replace motor.
5. Replace or tighten belt.
1. Add refrigerant.
2. Check refrigerant charge and check or replace
filters.
3. Clean or replace filters.
4. Replace power head.
5. Check low-pressure setting.
6. Remove obstruction.
1. Check unloader adjustments and Check unloader
setting.
2. See compressor service literature.
3. Check for open doors or windows in vicinity of fan
coil.
1. Add refrigerant.
2. Replace control.
3. Purge and evacuate system.
4. Clean or replace.
1. Support piping as required.
2. Check valve plates for valve noise. Replace
compressor if bearings are worn.
1. Repair leak.
2. Check wiring and relays. Check heater and replace
if defective.
3. Check piping for oil return. Replace if necessary
Adjust expansion valve
1. Repair leak and recharge.
2. Adjust expansion valve.
1. Remove restriction or replace.
2. Replace valve.
1. Replace unloader.
2. Replace valve.
3. Rewire correctly.
4. Replace spring.
1. Rewire correctly.
2. Replace valve.
3. Clean or replace strainer.
4. Clean or replace the necessary parts.