Heatcraft Refrigeration Products H-IM-CU System Troubleshooting Chart, Problem, Possible Causes

Table 10. System Troubleshooting Chart

Problem

Possible Causes

Possible Corrective Steps

Compressor will not	1. Main switch open.		1.	Close switch.
run	2. Fuse blown.		2.	Check electrical circuits and motor winding for shorts or grounds.
				Investigate for possible overloading. Replace fuse after fault is corrected.
	3.	Thermal overloads tripped.	3.	Overloads are automatically reset. Check unit closely when unit
				comes back on line.
	4.	Defective contactor or coil.	4.	Repair or replace.
	5.	System shut down by safety devices.	5.	Determine type and cause of shutdown and correct it before
				resetting safety switch.
	6.	No cooling required.	6.	None. Wait until calls for cooling.
	7.	Liquid line solenoid will not open.	7.	Repair or replace coil.
	8.	Motor electrical trouble.	8.	Check motor for open windings, short circuit or burn out.
	9.	Loose wiring.	9.	Check all wire junctions. Tighten all terminal screws.
	10. Phase loss monitor inoperative.		10. Refer to page 17.
Compressor noisy or	1. Flooding of refrigerant into crankcase.		1.	Check setting of expansion valves.
vibrating	2. Improper piping support on suction or liquid line.		2.	Relocate, add or remove hangers.
	3.	Worn compressor.	3.	Replace.
	4.	Scroll compressor rotation reversed.	4.	Rewire for phase change.
High discharge	1. Non-condensables in system.		1.	Remove the non-condensables.
pressure	2. System overcharges with refrigerant.		2.	Remove excess.
	3.	Discharge shutoff valve partially closed.	3.	Open valve.
	4.	Fan not running.	4.	Check electrical circuit.
	5.	Head pressure control setting.	5.	Adjust.
	6.	Dirty condenser coil.	6.	Clean.
Low discharge	1. Faulty condenser temperature regulation.		1.	Check condenser control operation.
pressure	2. Suction shutoff valve partially closed.		2.	Open valve.
	3.	Insufficient refrigerant in system.	3.	Check for leaks. Repair and add charge.
	4.	Low suction pressure.	4.	See corrective steps for low suction pressure.
	5.	Variable head pressure valve.	5.	Check valve setting.
High suction	1. Excessive load.		1.	Reduce load or add additional equipment.
pressure	2. Expansion valve overfeeding.		2.	Check remote bulb. Regulate superheat.
Low suction pressure	1. Lack of refrigerant.		1.	Check for leaks. Repair and add charge.
	2.	Evaporator dirty or iced.	2.	Clean.
	3.	Clogged liquid line filter drier.	3.	Replace cartridge(s).
	4.	Clogged suction line or compressor suction gas strainers.	4.	Clean strainers.
	5.	Expansion valve malfunctioning.	5.	Check and reset for proper superheat.
	6.	Condensing temperature too low.	6.	Check means for regulating condensing temperature.
	7.	Improper TXV.	7.	Check for proper sizing.
Little or no oil	1. Clogged suction oil strainer.		1.	Clean.
pressure	2. Excessive liquid in crankcase.		2.	Check crankcase heater. Reset expansion valve for higher superheat.
				Check liquid line solenoid valve operation.
	3.	Low oil pressure safety switch defective.	3.	Replace.
	4.	Worn oil pump.	4.	Replace.
	5.	Oil pump reversing gear stuck in wrong position.	5.	Reverse direction of compressor rotation.
	6.	Worn bearings.	6.	Replace compressor.
	7.	Low oil level.	7.	Add oil and/or through defrost.
	8.	Loose fitting on oil lines.	8.	Check and tighten system.
	9.	Pump housing gasket leaks.	9.	Replace gasket.
Compressor loses oil	1. Lack of refrigerant.		1.	Check for leaks and repair. Add refrigerant.
	2.	Excessive compression ring blow by.	2.	Replace compressor.
	3.	Refrigerant flood back.	3.	Maintain proper superheat at compressor.
	4.	Improper piping or traps.	4.	Correct piping.
Compressor thermal	1. Operating beyond design conditions.		1.	Add components to bring conditions within acceptable limits (i.e.,
protector switch				CPR/EPR valves, additional condenser surface, liquid injection, etc.).
open	2. Discharge valve partially shut.		2.	Open valve.
	3.	Blown valve plate gasket.	3.	Replace gasket.
	4.	Dirty condenser coil.	4.	Clean coil.
	5.	Overcharged system.	5.	Reduce charge.

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