Carrier 38AE - Manual (Page 10)

TROUBLESHOOTING (cont)
PROBLEM SOLUTION
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 coll partially iced
6. Indoor airflow restricted
Suction Pressure High
1. Compressor valve defective
2. Head load excessive
1 . Add refrigerant
2. Check refrigerant charge.
Check outdoor-air fan thermostat settings.
3 Clean or replace filters.
4. Replace power head.
5. Check low-pressure setting.
6. Remove obstruction.
1 . See 06D compressor service literature.
2 Check for open doors or windows in vicinity of fan coil.
UNIT OPERATES TOO LONG OR CONTINUOUSLY
1. Low refrigerant charge
2. Control contacts fused
3. Air in system
4. Partially plugged expansion valve or filter drier
1. Add refrigerant.
2. Replace control.
3. Purge and evacuate system.
4. Clean or replace.
SYSTEM IS NOISY
1. Piping vibration
2. Compressor noisy
1. Support piping as required.
2. Check valve plates for valve noise Replace compressor if bear­
ings are worn
COMPRESSOR LOSES OIL
1. Leak in system
2. Crankcase heaters not energized during shutdown
3. Improper interconnecting piping design
1 . Repair leak.
2. Check wiring and relays Check heater and replace if defective.
3 Check piping for oil return. Replace if necessary.
FROSTED SUCTION LINE
1. Expansion valve admitting excess refrigerant
1 . Adjust expansion valve.
HOT LIQUID LINE
1. Shortage of refrigerant due to leak
2. Expansion valve opens too wide
1 . Repair leak and recharge.
2. Adjust expansion valve.
FROSTED LIQUID LINE
1. Restricted filter drier
1 . Remove restriction or replace.
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
1 Replace unloader.
2 Replace valve.
3 Rewire correctly.
4. Replace spring
COMPRESSOR 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. Rewire correctly.
2. Replace valve.
3 Clean or replace strainer.
4 Clean or replace the necessary parts
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