Emerson Figure i manual 5.0TROUBLESHOOTING, Troubleshooting

Troubleshooting

5.0TROUBLESHOOTING

Table 23 Troubleshooting

Problem	Cause	Remedy
	No power to unit	Check voltage at input terminal block.
		Check for 24VAC ±2VAC at control connections 1 & 2. If
		no voltage, check control setting requires cooling. If there
Unit will not start	Compressor contactor not pulling in	is voltage, lockout relay may be energized. Check for
		24VAC at control connections 2 & 3. If there is voltage,
		see compressor high-discharge pressure/lockout relay.
	Control voltage circuit breaker (at
	transformer in evaporator module)	Locate short and reset circuit breaker.
	open
	Short cycle prevention control	Control software delays compressor 3 minutes from stop
		to start.
		Check for 24VAC ±2VAC at control connections 2 & 3.
	Compressor high discharge	Remove 24VAC signal at Connection 2 by turning indoor
		unit control off, then back on, or by raising the setpoint to
	pressure/ lockout relay
		remove the cab for cooling, then resetting to re-establish
		operation.
High discharge	Insufficient air flow across	Check fan operation. Remove debris from coil and air
	condenser coil	inlets.
pressure
	High refrigerant charge	Check refrigerant charge.
Low discharge pressure	Faulty head pressure control valve	Replace if defective.
	Compressor rotation in reverse	Check for proper power phase wiring to unit and to
	direction	compressor motor.
	Insufficient refrigerant in system	Check for leaks; repair and add refrigerant.
Low suction pressure /	Plugged filter drier	Replace filter drier.
		Reset expansion valve for 10-15°F (5.6 to 8.4°C)
compressor cycling	Improper superheat adjustment
		superheat at evaporator.
	Defective liquid line solenoid valve	Check valve and coil; replace if necessary.
	Defective liquid line solenoid valve	Check valve and coil; replace if necessary.
	Plugged filter drier	Check pressure drop across filter drier. Replace filter
Low compressor		drier.
capacity/ no cooling		Check for normal system operating pressures. Refer to
	Low refrigerant charge	abnormal pressure causes if applicable. Check for leaks.
		Proper refrigerant charge is very important at low ambient
		operation.
	Loose compressor or piping	Tighten clamps.
Compressor noisy	support
	Compressor rotation in reverse	Check for proper power phase wiring to unit and to
	direction	compressor motor.
Pipe Rattle	Loose pipe connections	Check pipe connections.
Compressor running hot	Compression ratio too high	Check for normal system operating pressures. Refer to
		abnormal pressure causes if applicable.
	High discharge pressure	Check for blocked condenser fan or coil.
	High suction temperature	Check expansion valve and hot gas bypass valve setting.
Compressor motor		Check liquid quenching valve operation.
protectors tripping or
	Loose power or control circuit	Check all power and control circuit connections.
cycling	wiring connection
	Defective motor	Check for motor ground or short. Replace compressor if
		either condition is found.
	Low line voltage	Check line voltage and determine location of voltage drop.
Compressor cycles on	Compressor motor defective	Check for motor winding short or ground.
locked rotor
	Single phasing	Check voltage across all 3 legs at contactor. Correct
		source of problem.
	Check control panel for welded
Motor burnout	contactor contacts or welded	Replace defective components.
	overload contacts.

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