TroubleCompressor will not run(Cont’d)Possible Cause4. Fuses blown.5.Over-load relays tripped.Corrective Measure4.Test fuses and renew if necessary.5.Re-set relays and find cause ofoverload.6. Low voltage.6.Check voltage (should be within10 percent of nameplate rating).7.Electrical motor in trouble.7.Repair or replace motor.8.Trouble in starting switch or8. Close switch manually to testcontrol circuit.power supply. If OK, check controlcircuit including temperature andpressure controls.9.Compressor motor stopped by oil9.Check oil level inpressure differential switch.crankcase. Check oil pumppressure.Sudden loss of oil fromcrankcase.Capacity reduction systemfalls to unload cylinders.Liquid refrigerant slugging back toAdjust or replace expansion valve.compressor crank case.Hand operating stem of capacitySet hand operating stem to automaticcontrol valve not turned to automaticposition.position.Compressor continues toPressure regulating valve not opening.Adjust or repair pressure regulatingoperate at full or partial load.valve.Capacity reduction systemBroken or leaking oil tube betweenRepair leak.fails to load cylinders.pump and power element.Compressor continues toPressure regulating valve not closing.Adjust or repair pressure regulatingoperate unloaded.valve.Figure 5-9.—Trouble diagnosis chart-Continued.possible causes and corrective measures. Figure 5-10also lists some of the problems, causes, and correctivemeasures and includes recommended test proceduresthat may be used to isolate the problems.SAFETY PRECAUTIONS USED WHENHANDLING REFRIGERANTSThe following safety precautions are the minimumrequired when you are using refrigerants:1. Two people must be present at all times whilerefrigerant is being charged into a refrigeration system.NEVER leave the area unattended while charging is inprogress.2. Ensure that ventilation in the space is adequateto keep the concentration of refrigerant below 1,000parts per million. If necessary, use portable blowers.3. If refrigerant is being charged into or beingremoved from a system, prohibit all nonessential5-15
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