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The most common causes of air conditioner failure to “start" are:-

a) Voltage not within ±10% of rated voltage.

b) Power supply interrupted.

c) Control settings improper.

d) Air conditioner is disconnected from main power source.

e) Fuse blown or circuit breaker off.

II) DIAGNOSIS OF REFRIGERANT CIRCUIT / APPLICATION

There might be some cases where the unit starts running but does not perform satisfactory,

i.e. insufficient cooling. Judgement could be made by measuring temperature difference of

indoor unit's intake and discharge air as well as running current.

Insufficient Cooling

Unit Starts

Excessive heat

source e.g.

electric kettle

High heat load

Refrigerant circuit

Leakage

Restriction e.g. at

strainer, capillary,

filter dryer, etc.

Compressor

Less or no compression

(Low running current)

Room

overcrowded with

people

Windows / doors

wide open

Check air circulation

Indoor/Outdoor coil dirty (clogged)

Air filters dirty

Fan Malfunction

Obstruction at air inlet/outlet of

indoor/outdoor unit

Satisfactory operation with temperature difference of air

intake & discharge of indoor unit 8°C - 13°C

Insufficient Heating