Unit 41 Air Conditioning Cooling Troubleshooting Review Questions

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HVAC 240 Unit 41

41. 1 Introduction • Troubleshooting air conditioning equipment involves mechanical & electrical systems • Symptoms may overlap • Technicians must diagnose problems correctly - systematically

41. two Mechanical Troubleshooting • Gages & thermometers used when doing mechanical troubleshooting • R-22 and 410 A most common refrigerant used in ac equipment • R-22 t/p chart printed on each gage

Approaching temperature and Temperature difference • Air leaving the evaporator is about 17*-xx* cooler than inbound • Your split should be 20* for R-22 and 25* for 410 A

41. 4 Cuff manifold usage • Displays depression & high side pressures • Pressures are converted to saturation temps for evaporating refrigerant & condensing refrigerant • Two types of pressure connections: • Schrader valve, Service valve Note: Service valves can exist used to isolate the refrigerant

41. 4 When to Connect Gages • Gage manifolds non continued every time system serviced • Modest amounts of refrigerant escape each fourth dimension gages continued • Short gage hoses limit corporeality of refrigerant loss • Employ isolation valve to limit loss- peculiarly on liquid line

41. four When to Connect Gages • Gage manifolds non connected every time system serviced • Minor amounts of refrigerant escape each time gages connected • Short cuff hoses limit amount of refrigerant loss • Apply isolation valve to limit loss- especially on liquid line

41. half dozen Depression Side Gage Readings • Used to compare actual evaporating pressure to normal evaporating pressure • Low side reading verifies refrigerant boiling at correct temp at current load status • Standard efficiency systems unremarkably have boiling temp ~30 -35*F cooler than entering air temp at standard operating condition of 75*F return air with fifty% RH • Space temp out of these ranges crusade oversized load on evaporator

41. 7 High Side Gage Readings • Used to check relationship of condensing refrigerant to ambient air temperature • Standard air cooled condensers no more than xxx*F college than AA • Bank check actual outside air temperature • High efficiency condensers operate at lower pressures & condensing temps • TD of thirty*

41. 8 Temperature Readings • Useful when checking performance of air workout equipment • Temps volition vary from system to system • Mutual temps used for evaluation: Suction-line temperature Condenser outlet-line temperature Compressor discharge-line temperature

Temperature readings 90* summer mean solar day readings R 22 coil temp 40* or 70 psi (low side) condenser temp 125* or 275 psi (high side) R 410 A coil temp 40* or 120 psi (low side) condenser temp 125* or 400 psi (high side)

41. nine Charging Procedures in Field Right charge consists of enough refrigerant in: • Evaporator- Superheat • Suction line • Liquid line • Belch line • Condenser- Subcooling

41. 9 Charging procedures in field Annotation: under charge volition crusade high superheat and depression subcooling Over charge will cause low superheat and high subcooling

41. 10 Electrical Troubleshooting Volt, Ohms, Amps meter • Tech must know what readings should be • Control voltage stepped downwards to 24 volts • Begin any electrical troubleshooting past verifying that the power supply is energized • If the power supply voltage is correct, motility on to the various components • Checking electrical circuits in parallel should exist checked separately

41. xi Compressor Overload Problems • When compressor overload protector is open, touch motor housing to see if hot • The compressor can be cooled past running cold h2o over the top of it, water ice purse it or past disconnecting it and allowing information technology to cool • Cooling compressor by running water over it may take thirty minutes or longer- commonly longer

41. 12 Compressor Electric Checkup Introduction • Check the motor windings with ohmmeter • Refer to manufacturer's specifications for correct winding resistance values • Compressor may have: Shorted winding Open up winding Grounded winding

41. 13 Troubleshooting the Excursion Electrical Protectors – Fuses and Breakers • Compressors & fan motors have protection to guard from small problems • Exercise non reset or replace tripped breaker or fuse without determining what acquired information technology to trip or blow

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