Specifications

91
No Cooling / Heating
Unit fail to start
Check power supply
- voltage
- phase
- frequency
Check settings of remote control box
Compressor fails to start
Check circuit breake & fuse
Check power source cord
Fan fails to start
Fan Motor Capacitor defective
Loose Connections,
Contactors
Irregular motor resistance ( Ω )
& insulation (M Ω )
Replace Fan Motor
Compressor Motor damaged ( to replace compressor)
Thermostat setting too high
Protection Device Actuated
Reset
Compressor locked (to replace compressor)
Voltage supply not within range
Check motor resistance ( Ω ) and insulation (M Ω )
Compressor
Capacitor Defective
Loose Connections,
Improper wiring
Regular but fails
to start
Irregular
Troubleshooting
By means of pressure readings :
PRESSURE
PROBABLE CAUSE
Data
Circuit
Too Low A Little Low Normal A Little High Too High
High Side
Low Side
=
=
1. Overcharged with refrigerant.
2. Non-condensable gases in refrigerant circuit (e.g. oil).
3. Obstructed air-intake/discharge.
4. Short circuiting of hot air at condensing unit.
High Side
Low Side
=
=
1. Poor compression/no compression (compressor defective.)
2. Check valve stick in open position.
3. Reversing valve leaking.
High Side
Low Side
=
=
1. Undercharged with refrigerant.
2. Refrigerant leakage.
3. Air filter clogged/dirty (indoor unit).
4. Indoor fan locked (cooling).
5. Defective defrost control, outdoor coil freezed up (heating).
6. Outdoor fan locked (heating).
High Side
Low Side
=
=
1. Outdoor fan blocked (cooling).
2. Outdoor coil dirty (cooling).
3. Indoor fan locked (heating).
4. Indoor filter clogged/dirty (heating).
5. Non-condensable gases in refrigerant circuit (e.g. air).
High Side
Low Side
=
=
1. Air intake temperature of indoor unit too high.
By means of diagnosis flow chart
Generally, there are two kinds of troubles, i.e. starting failure and insufficient cooling/heating. "Starting Failure" is
caused by electrical defect while "Insufficient Cooling/Heating" is caused by improper application or defects in
refrigerant circuit.
1. Diagnosis of electric circuit