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– 55 –

Note: Use an appropriate measuring instrument for readjustment.

*1:  Check the High-pressure switch indication.

*2: Check the Low- pressure switch indication.

Other parts than the unit

Outdoor coil

In-condensable gas
blended.

High pressure switch

Refrigerant

Outdoor Fan

Improper opening of the
service valves in the
refrigerant line

Coil is dirty *1

Air intruded into the 
refrigerant pipe line *1

Improper adjustment

A shortage of refrigerant
amount. * 2

Reverse rotation of fan 
Obstacle
Air short circuit *1

Checking

Checking

In the event that 
difference between the
saturating temperature
corresponding to high
pressure and the 
temperature of air 
discharged from the 
outdoor coil is more than
15°C, incondensable gas
may be blended.

Check it with a pressure
gauge.

Confirm the wind blowing
out.

Check it with eyes.

Open it properly

Wash it by means of
something like chemical
washing.

Extract air by vacuum
pump, then recharge the
refrigerant.

Readjust it to normal
operating pressure. 
(Note)
Don't alternate the 
specified adjusting 
pressure. If the adjusted
pressure exceeds the
specified range, it will
cause a great accident.

Recharge the 
refrigerant. Repair the
spot where it leaks.

If reversed, connect
interchanged wires to
each terminal. 
Power wirings.

– 56 –

Load

Air flow

Short air volume

Refrigerant

Air passage

Air filter

Much heat load

Obstacle disturbs Intake
of uniform wind.

Reverse rotation of 
blower.

Shortage in the charged
refrigerant.

Improper or foreign bodies

Clogged with dust

Heat load increased. 
Window or door has many
cracks or gaps.

Checking

Checking

Coil inlet pipe is frosted 

Checking

Checking

Do necessary disposal
respectively.

Correct it.

Correct it.

Replenish it. 
(Repair the leakage spot).

Correct or clear the 
foreign bodies.

Cleaning

Compressor

Blower

Screws

• Checking

• Checking

Checking

Checking

• Remove the shipping

bracket.

• Replace the 

compressor

• Repair or replace it.
• Clear the other 

material

Repair

Liquid refrigerant flooding
back from the evaporator.

Compressor shipping
bracket is not removed.

Faulty discharge valve
and suction valve.

Fan broken.

Other materials intruded.

Looseness or fail-off of
screws

• Check for refrigerant over-charge.
• Check to see if the intaking air temperature is

extremely cold.

• Check for insufficient air flow quantity.

– 57 –

Electric troubles
(Magnetic 
contactor)

Others

Defective contact.
Defective contact point.
Rusting and faults in the iron
core contact face. Defective
contact of the 
operating switch.

Improper installation

Checking

Checking

Repair and clean or
replace it.

Correct it.

High Discharge

Low 
Discharge

High 
Suction
Pressure

Low 
Suction
Pressure

Condenser cooling air extremely hot or
insufficient air flow through the condenser

Inside of the condenser tube is clogged.

Air in the refrigeration cooling cycle.

Suction pressure is higher than standard.

Faulty discharge valves or suction valves of
the compressor.

Refrigerant low-charge or leakage.

Suction pressure is lower than standard.

Intake air extemely hot or excessive air flow
through the evaporator coil.

Refrigerant over-charge.

Faulty discharge valve or suction valve of
the compressor.

Discharge pressure is higher than standard

Intake air extremely cold or insufficient air
flow through the evaporator coil.

Refrigerant short-charge or leakage.

Restricted liquid in the suction line.

1. Check the operation of the outdoor motor.
2. Check discharge and suction, air circula-

tion.

Clean condenser coil.

Purge air from the cycle.

See "High Suction Pressure".

1. Check unit operation input

2. Check the suction pressure.

Add refrigerant: repair leakage if any.

See "Low Suction Pressure".

1. Check fresh air, intake or check for

leakage of the return air.

2. Check air flow quantity.

Purge the refrigerant.

Check the operating input.

See "High discharge Pressure".

1. Check air flow quantity.

2. Check air filter.

3. Check evaporator coil frosting

Add refrigerant, repair leakage, if any.

Check the capillary tube and the strainer.

– 58 –

Overcurrent
Relay for
Compressor
Cut-Off

Overcurrent
Relay for
Fan Motor
Cut-Off

Fuse Blown

Disconnection
and Faulty
Contact

Discharge pressure is lower than standard.

Single or three phases running.

High or low voltage or phase unbalance.

Refrigerant short charge or leakage. 

Compressor frequently stops and starts.

Discharge and suction pressure are
extremely high.

High or low voltage, or phase unbalance.

Single or three phases running

Faulty compressor motor.

Loose connections.

Compressor frequently stops and starts.

High or low voltage, or phase unbalance.

Single or three phases running.

Faulty fan motor.

Loose connection.

Faulty fan bearing.

Loose connections.

Single or three phase running.

Faulty motor.

Disconnection.

Faulty contact.

See "Low Discharge Pressure".

Check the power supply line and the 
contactor.

Check the voltage and phase unbalance.

Add refrigerant, repair leakage, if any.

Check thermistor operation, or any other
cause for frequent stop and start operation.

See "High Discharge Pressure" or "High
Suction Pressure".

Check the voltage and phase unbalance.

Check the power supply line and the 
contact.

Check electric resistance among the 
compressor terminals, and from the ter-
minals to ground.

Check the electric connections.

Check the operation of the thermistor, or
any other cause for frequent stop.

Check the voltage and electric wiring.

Check the power supply line and the 
contactor.

Check the fan motor and wiring.

Check the elelctric connections.

Check repair or replace the bearing.

Check the electric connections.

Check the power supply line.

Check electric resistance among motor
housing, and from the terminals to
ground.

1. Check the wires and connect where 

necessary.

2. Check the contact holding coil.

Check the contact in the magnetic con-
tact, the over-current relay, the pressure
control switch, the operation switch, the
auxiliary relay.