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Maintenance
Table 10. Troubleshooting methods (continued)
Symptom
Noisy Compressor
Compressor Fails to Start
System Short of Capacity
Compressor Short Cycles
Heater Inoperative
42
Probable Cause
a. Expansion valve stuck in open position
(abnormally cold suction line).
b. Worn or scarred compressor bearings.
c. Liquid slugging.
d. Scroll compressor not properly phased.
a. Temperature set point too high.
b. Compressor internal overload protector is
open.
c. Complete loss of refrigerant charge (low
pressure safety switch).
d. Condenser pressure too high (high pres- sure
safety switch).
e. Condensate switch open.
a. Low refrigerant (indicated by bubbles in sight
glass).
b. Expansion valve stuck or obstructed (short
cycling or continuous running).
c. Clogged drier/strainer (feels cold).
d. Reduced airflow
a. Low line voltage causing compressor to
overheat.
b. Dirty or iced over evaporator coil.
c. Reduced airflow (when applicable).
d. Lack of refrigerant.
e. Short cycling of conditioned air.
f. Thermostat is improperly located.
a. Fuses blown/circuit breaker tripped.
b. Thermostat set too low.
c. Overheat switch open due to insufficient
airflow across heater elements.
d. Fuse link blown.
e. Heater element burned out.
Recommendation
Ensure feeder bulb is tight on suction line.Check
operation and superheat.
Replace compressor.
System overcharged. Reclaim excess refrigerant.
Phase correctly at main power source. Do not
rewire compressor.
Adjust to desired temperature.
Check compressor for short circuit or ground.
Locate and repair leak. Recharge system.
Check condenser for obstructions.
1. Ensure unit is level.
2. Check that condensate pan is draining
properly. Clear obstructions.
Check for leaks. Repair and recharge system.
Remove valve and clear obstruction or replace
valve.
Replace with new drier/strainer.
Check belt tension, filters and clear evaporator
coil of debris.
Check power source for cause of low line voltage.
Defrost and/or clean coil.
Check filter and belt tension.
Check for leak. Repair and recharge system.
1. Supply and/or return grilles are incorrectly
oriented. Re-orient.
2. Supply and return grilles are too close
together. Move farther apart.
3. Insufficient heat load. Add temporary heat
load to compensate.
Check for supply registers that may be too close
to thermostat. Relocate if necessary.
Check for short circuit; replace fuses/reset circuit
breaker.
Increase temperature setpoint.
Check for dirty filters or obstructions that may
reduce airflow. Correct or replace as needed.
Replace fuse link (see item immediately
above).
Check continuity with an ohmmeter. Replace
heater element.
AH-SVX008C-EN
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