service section technical training. air conditioning troubleshooting

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Air Conditioner TroubleshootingAir Conditioner Troubleshooting

Service SectionService Section

Technical Training Technical Training

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Air Conditioning Air Conditioning TroubleshootingTroubleshooting

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Air Conditioning System

• Electrical circuitElectrical circuit

• Refrigerant circuitRefrigerant circuit

An air conditioning system can be An air conditioning system can be divided into 2 main functioning groupsdivided into 2 main functioning groups

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Air Conditioning System

To troubleshoot a system, one must have To troubleshoot a system, one must have to adopt “divide and conquer” techniqueto adopt “divide and conquer” technique

• Divide the “Big” problem into multiple smaller Divide the “Big” problem into multiple smaller problemsproblems

• Solve each of the problem individuallySolve each of the problem individually

• Put electrical problem in first priorityPut electrical problem in first priority

• A main point to take note is that if a system do A main point to take note is that if a system do not start, the faulty must be from electrical faultnot start, the faulty must be from electrical fault

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Troubleshooting electrical faults

Always ask a lot of questions and do not Always ask a lot of questions and do not make assumption before we checkmake assumption before we check

• Is the power supply being switch on / being Is the power supply being switch on / being connected ?connected ?

• Is the wiring being done properly?Is the wiring being done properly?

• Is the wire loose ?Is the wire loose ?

• Is there any signal coming from controller or Is there any signal coming from controller or thermostat ?thermostat ?

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1) Unit will not start1) Unit will not start

• Main power supply fail ? Voltage fluctuation ?Main power supply fail ? Voltage fluctuation ?

• Blown fuse or varistor ?Blown fuse or varistor ?

• Faulty transformer ?Faulty transformer ?

• Loose connections ?Loose connections ?

• Shorted or broken wires ?Shorted or broken wires ?

• Safety device opens ?Safety device opens ?

• No signal from thermostat/controller ?No signal from thermostat/controller ?

• Faulty thermostat ?Faulty thermostat ?

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2) Some components do not start2) Some components do not start

• Loose connections ?Loose connections ?

• Shorted or broken wires ?Shorted or broken wires ?

• No signal from thermostat/controller ?No signal from thermostat/controller ?

• Faulty magnetic contactor ?Faulty magnetic contactor ?

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3) Controller/thermostat3) Controller/thermostat

• A clear understanding of the functional A clear understanding of the functional specification of the controller/thermostat is specification of the controller/thermostat is crucial.crucial.

• Setting of the controller/thermostat must be Setting of the controller/thermostat must be obtained.obtained.

• Operating temperatures must be obtained (exp: Operating temperatures must be obtained (exp: room, return air, ambient, water, etc.)room, return air, ambient, water, etc.)

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Troubleshooting refrigerant faults

Some of the major problems found in a air Some of the major problems found in a air conditioning systemconditioning system

• The air conditioner runs but shortly stopsThe air conditioner runs but shortly stops

• The air conditioner short cycles with insufficient The air conditioner short cycles with insufficient coolingcooling

• The air conditioner runs continuously with The air conditioner runs continuously with insufficient coolinginsufficient cooling

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Three main conditions in the air Three main conditions in the air conditioners that are operating but not conditioners that are operating but not cooling satisfactorily are cooling satisfactorily are

• High discharge pressureHigh discharge pressure

• Low suction pressureLow suction pressure

• High suction pressureHigh suction pressure

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1) High discharge pressure1) High discharge pressure

• Dirty or partially blocked condenserDirty or partially blocked condenser

• Air or other non-condensable gases in Air or other non-condensable gases in refrigeration cyclerefrigeration cycle

• Overcharge of refrigerantOvercharge of refrigerant

• Insufficient condensing mediumInsufficient condensing medium

• High temperature condensing mediumHigh temperature condensing medium

• Short cycling of condensing airShort cycling of condensing air

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2) Low suction pressure2) Low suction pressure

• Insufficient air or heat load on evaporator coilInsufficient air or heat load on evaporator coil

• Resistance against refrigerant flowResistance against refrigerant flow

• Shortage of refrigerantShortage of refrigerant

• Faulty capillary tube or expansion valveFaulty capillary tube or expansion valve

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3) High suction pressure3) High suction pressure

• Heavy load conditionsHeavy load conditions

• Unit undersized for applicationUnit undersized for application

• Low superheat adjustmentLow superheat adjustment

• Improper expansion valve adjustmentImproper expansion valve adjustment

• Poor installation of feeler bulbPoor installation of feeler bulb

• inefficient compressorinefficient compressor

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Some of the problems of refrigerant Some of the problems of refrigerant system can be diagnose through the use system can be diagnose through the use of pressure gauge and also an ammeterof pressure gauge and also an ammeter

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H.P

L.P

AMP

• Both high and low pressure are very high• Running current increase extremely

Pressure and running current reading

• Refrigerant overcharged >> Wet operation

Main causes of troubles

* In case refrigerant overcharged excessively, high pressure switch or overcurrent relay functions

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H.P

L.P

AMP

• Discharge pressure is very high• Suction pressure is a little higher than normal• Running current increases


• 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

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H.P

L.P

AMP

• Discharge pressure is a little higher than normal• Suction pressure is very high• Running current increases


• Unit undersized for application• Heavy load condition


* High suction air temperature >> superheated operation

• Excessive air flow rate• Excessively opened expansion valve >> wet operation

* Poor installation of feeler bulb* Low superheat adjustment

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H.P

L.P

AMP

• Discharge pressure is a little lower than normal• Suction pressure is very low• Running current decreases


• Shortage of refrigerant• Restricted refrigerant flow


* 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

* Frost grows on evaporator coil

>> superheated operation

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H.P

L.P

AMP

• Discharge pressure is a little lower than normal• Suction pressure is very low• Running current decreases


• Insufficient heating medium >> wet operation

Main causes of troubles (continue)

* 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

* Frost grows on evaporator coil

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H.P

L.P

AMP

• Discharge pressure is a little lower than normal• Suction pressure is very high• Running current decreases


• Malfunction of compressor >> super heated operation


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H.P

L.P

AMP

• Both high and low pressures are very low• Running current decreases extremely


• Extreme refrigerant shortage >> super heated operation


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Liquid refrigerant comes back to the compressor

Liquid compression

Vane or valve failure

Insufficient lubrication(washed out)

Refrigerant is dissolved in oil

Oil foaming

Bearing failure

Motor coil insulation is being eroded

Motor coil failure

Wet operation

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Suction and discharge gas temperature is higher than the normal

Oil temperature becomes higher

Carbonization of oil

Incomplete seat action

Oil viscosity drops

Insufficient lubrication

Bearing failure

Insufficient cooling for motor coil

Motor coil failure

Super heated operation

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Thank youThank you

service section technical training. air conditioning troubleshooting

Documents

condensing air slide

air conditioners

electrical fault slide

ammeter slide

stopsthe air conditioner

problems of refrigerant

insufficient cooling

expansion valve slide