NANO

906 / 1980

HVAC
853
HVAC
REFRIGERATING CYCLE TROUBLE-
SHOOTING
1. INSUFFICIENTREFRIGERANT
Condition
• Air conditioner does not cool effectively
Symptoms in refrigerant cycle
• Pressure on both the high and low pressure
sides is low
• Air around the air outlet is slightly cold
Cause
• There is gas leakage in the refrigerating cycle
Diagnosis
• Insufficient refrigerant in the refrigerating cycle
• Refrigerant leakage
Countermeasures
• Locate the leaking and repair
• Recharge refrigerant to the specified amount
2. EXCESSIVE REFRIGERANT OR INSUFFICIENT
CONDENSER COOLING
Condition
• Air conditioner does not cool effectively
Symptoms in refrigerant cycle
• Pressure on both the high and low pressure
sides is high.
Cause
• Refrigerant is overcharge in the refrigerating cycle,
causing poor cooling performance.
• Condenser cooling performance is poor
• Fluid coupling on fan is slipping
Diagnosis
• Excessive refrigerant in the refrigerating cycle
• Overcharged refrigerant
• Poor condenser cooling performance
• Condenser fins blocked or fan belt loose
• Slipping radiator fan fluid coupling
• Silicone oil leaking from the coupling
Countermeasures
• Clean the condenser
• Tighten the AC belt to the correct tension
3. ENTRY OF MOISTURE IN THE REFRIGERANT
CYCLE
Condition
• Air conditioner alternately cools and does not
cool
Symptoms in refrigerant cycle
• During operation, the pressure on the low pressure
side alternates between vacuumand normal
Cause
• The moisture mixed in the refrigerant in the
refrigerating cycle freezes in the expansion valve
orifice, blocking the cycle. After a time, the ice
melts and normal conditions return
Diagnosis
• The drier is in an oversaturated condition
• The moisture in the refrigerating cycle freezes
the expansion valve orifice, impeding refrigerant
circulation
Countermeasures
• Remove the moisture by repeated evacuation
• Recharge new refrigerant to the specified amount
4. REFRIGERANT FAILSTOCIRCULATE
Condition
• Air conditioner does not cool
Symptoms in refrigerant cycle
• Pressure on the low pressure side is vacuum
and pressure on the high pressure side is
extremely low
• Frost or dew is formed on the piping at the front
and rear side of the receiver or the expansion
valve
Cause
• Moisture or dirt in the refrigerating cycle freezes or
sticks to the expansion valve orifice, obstructing
refrigerant flow.
• Gas leaking from the heat sensitizing tube of the
expansion valve obstructs refrigerant flow
Diagnosis
• Blocked expansion valve orifice
Countermeasures
• Allow to stand for some time and then resume
operation to decide whether the blockage is caused
bymoisture or by dirt. If caused bymoisture; remove