Service Section Technical Training

Air Conditioning Troubleshooting

Air Conditioning System An air conditioning system can be divided into 2 main functioning groups Electrical circuit Refrigerant circuit Electrical - power supply, controls Refrigerant - close circuit, components

Air Conditioning System To troubleshoot a system, one must have to adopt “divide and conquer” technique Divide the “Big” problem into multiple smaller problems Solve each of the problem individually Put electrical problem in first priority A main point to take note is that if a system do not start, the faulty must be from electrical fault Use software programming as an example

Troubleshooting electrical faults Always ask a lot of questions and do not make assumption before we check Is the power supply being switch on / being connected ? Is the wiring being done properly? Is the wire loose ? Is there any signal coming from controller or thermostat ? Must make sure that the power supply is

Troubleshooting electrical faults 1) Unit will not start Main power supply fail ? Voltage fluctuation ? Blown fuse or varistor ? Faulty transformer ? Loose connections ? Shorted or broken wires ? Safety device opens ? No signal from thermostat/controller ? Faulty thermostat ? Must make sure that the power supply is

Troubleshooting electrical faults 2) Some components do not start Loose connections ? Shorted or broken wires ? No signal from thermostat/controller ? Faulty magnetic contactor ? Must make sure that the power supply is

Troubleshooting electrical faults 3) Controller/thermostat A clear understanding of the functional specification of the controller/thermostat is crucial. Setting of the controller/thermostat must be obtained. Operating temperatures must be obtained (exp: room, return air, ambient, water, etc.) Must make sure that the power supply is

Troubleshooting refrigerant faults Some of the major problems found in a air conditioning system The air conditioner runs but shortly stops The air conditioner short cycles with insufficient cooling The air conditioner runs continuously with insufficient cooling Must make sure that the power supply is

Troubleshooting refrigerant faults Three main conditions in the air conditioners that are operating but not cooling satisfactorily are High discharge pressure Low suction pressure High suction pressure Must make sure that the power supply is

Troubleshooting refrigerant faults 1) High discharge pressure Dirty or partially blocked condenser Air or other non-condensable gases in refrigeration cycle Overcharge of refrigerant Insufficient condensing medium High temperature condensing medium Short cycling of condensing air Must make sure that the power supply is

Troubleshooting refrigerant faults 2) Low suction pressure Insufficient air or heat load on evaporator coil Resistance against refrigerant flow Shortage of refrigerant Faulty capillary tube or expansion valve Must make sure that the power supply is

Troubleshooting refrigerant faults 3) High suction pressure Heavy load conditions Unit undersized for application Low superheat adjustment Improper expansion valve adjustment Poor installation of feeler bulb inefficient compressor Must make sure that the power supply is

Troubleshooting refrigerant faults Some of the problems of refrigerant system can be diagnose through the use of pressure gauge and also an ammeter Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Both high and low pressure are very high Running current increase extremely Main causes of troubles Refrigerant overcharged >> Wet operation * In case refrigerant overcharged excessively, high pressure switch or overcurrent relay functions Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Discharge pressure is very high Suction pressure is a little higher than normal Running current increases Main causes of troubles Insufficient condensing medium * Dirty condenser * Partially blocked condenser * Malfunction of condenser fan or fan motor * Reverse revolution of condenser fan * Short cycling of condensing air * High temperature condensing air Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Discharge pressure is a little higher than normal Suction pressure is very high Running current increases Main causes of troubles Unit undersized for application Heavy load condition * High suction air temperature >> superheated operation Excessive air flow rate Excessively opened expansion valve >> wet operation Must make sure that the power supply is * Poor installation of feeler bulb * Low superheat adjustment

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Discharge pressure is a little lower than normal Suction pressure is very low Running current decreases * Frost grows on evaporator coil Main causes of troubles Shortage of refrigerant Restricted refrigerant flow >> superheated operation * Expansion valve or capillary tube obstructed * Dryer or filter clogged with dirt * Valve in liquid line partially closed * Obstruction in liquid line * Leaking power element on expansion valve Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Discharge pressure is a little lower than normal Suction pressure is very low Running current decreases * Frost grows on evaporator coil Main causes of troubles (continue) Insufficient heating medium >> wet operation * Poor evaporating air flow rate - Dirty air filter - Slippage of fan belt - Reverse revolution of evaporator fan - Short cycling of cooling air * Light load condition - Low suction air temperature Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Discharge pressure is a little lower than normal Suction pressure is very high Running current decreases Main causes of troubles Malfunction of compressor >> super heated operation Must make sure that the power supply is

Troubleshooting electrical faults H.P L.P AMP Pressure and running current reading Both high and low pressures are very low Running current decreases extremely Main causes of troubles Extreme refrigerant shortage >> super heated operation Must make sure that the power supply is

Wet operation Liquid refrigerant comes back to the compressor Liquid compression Insufficient lubrication (washed out) Refrigerant is dissolved in oil Motor coil insulation is being eroded Oil foaming Vane or valve failure Motor coil failure Bearing failure

Super heated operation Suction and discharge gas temperature is higher than the normal Oil temperature becomes higher Carbonization of oil Oil viscosity drops Insufficient cooling for motor coil Incomplete seat action Insufficient lubrication Motor coil failure Bearing failure

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