PAC Maintenance

A. COMPRESSOR FAILS TO START1.  Power failure.1.  Electric circuit test shows no. current on lie side of motor starter.1.  Check for blown fuse or broken lead.
2.  Disconnect switch open.2.  Electric circuit test shows no current on line side of motor starter.2.  Determine why switch was opened, if everything O.K., close switch.
3.  Fuse blown.3.  Electric circuit test shows current on line side but not on motor side of fuse.3.  Replace fuse. Check load on motor.
4.  Low voltage.4.  Electric circuit tester glows but not at full brilliance.4.  Check with volt meter, then call power company.
5.  Burned-out motor.5.  Full voltage at motor terminals but motor will not run.5.  Repair or replace.
6.  Inoperative motor starter.6.  Test for burned-out holding coil or broken contacts.6.  Repair or replace.

7. Open control circuit.

 a.  Dual pressure control.

 b.  Oil failure control.

 c.  Motor starter thermal overloads.

 d.  Open circuit from interlocking relays.

7.  Motor starter holding is not energized.7.  Locate open control and determine cause. See individual instructions of LP/HP.
8.  Broken or sheared coupling.8.  Motor runs but compressor does not.8.  Repair or replace. Properly reeling.
9.  Frozen compressor due to locked or damaged mechanism.9.  Compressor will not operate.9.  Overhaul compressor.
10. Suction pressure below cut-in-setting of low pressure cut-out switch.10. Open contacts on low pressure switch. Suction pressure below cut-in setting.10. Check for loss of refrigerant. Repair leak and recharge.
11. Discharge pressure above cut-in-setting of high pressure cut-out switch.11.       Open contacts on high pressure switch. Discharge pressure above cut-in setting.11. Discharge pressure too high.
B. COMPRESSOR "SHORT CYCLE"1.  Intermittent contact in electrical control circuit.1.  Normal operation except too frequent stopping and starting.1.  Repair or replace faulty electrical control.
2.  Low pressure controller differential set too close.2.  Normal operation except too frequent stopping and starting.2.  Reset differential in accordance with proper job condition.
3.  High pressure controller differential too close.3.  Normal operation except too frequent stopping and starting.3.  Replace faulty control.
4.  Leaky liquid line value.4.  Valve may hiss when closed. Also temperature change in refrigerant line through valve.4.  Repair or Replace.
5.  Dirty or iced evaporator.5.  Reduced air flow :a.  Dirty air filters.b.  Broken fan c.  Fan belt tension.5.  Clean or defrost evapo. Check fan belt tens.
6.  Faulty condensing.Excessive disc. pressure.Check fans or water pumps.
7.  Over charge of ref.-do-     Remove excessive ref.
8.  Lack of ref.Frequent ON/OFFRepair leakage & charge ref.
9.  Restricted liquid line stranger.Suction press. too low.Clean or replace.
10. Cond. coil dirty.High disc. pressure Cleaning
C. COMPRESSOR RUNS CONTINUOUSLY1.  Excessive loadHigh temp. in cond. areaCheck for F/Air or additional load.
2.  Thermostat setting at too low tempLow temp. in cond. areaReset thermo.
3.  Welded contacts-do-Replace cont.
4.  Lack of ref.High temp. in cond. areaCheck leak repair & charge ref.
5.  Leakage in internal valves of comp.Low disc. & high suction press.Replace or repair
D. COMPRESSOR NOISY1.  Lack of oil Nose at comp.Add oil
2.  Internal parts broken or lose-do-Repair or replace
3.  Liquid flood backAbnormally cold suction line.Check the superheat, Exp. value Cooling coil
E. DISCHARGE PRESS. TOO HIGH1.  Dirty condenser coilTrippingClean
2.  Improper operation of condenser fan-do-Check fans blades, motor
3.  Air or non condensable gas in system-do-Purge
4.  Over charge of ref.-do-Remove
F.  DISCHARGE PRES. TOO LOW1.  Lack of ref.--------- -------Add. ref.
2.  Clogged strainer--------- -------Replace
3.  Internal valve leakage in compressor--------- -------Replace
G. SUCTION PRESS. TOO HIGH1.  Excessive load on evaporator-------- --------As mentioned at "C"-1
2.  Overfeeding of Exp.----------------Set superheat
3.  Exp. valve stuck open-------- --------Repair or replace
4.  Broken suction valve in compressor-------- ---------do-
H. SUCTION PRESS. TOO LOW1.  Leakage of ref.-------- --------Check leaks charge ref.
2.  Clogged cooling coil-------- --------Clean
3.  Exp. valve power assb. has lost charge/obstracteo------- ---------Replace
4.  Thermostat set at too low temp.Low temp in conditioned spaceCheck & reset
I.  SYSTEM SHORT OF CAPACITY1.  Under charge of condensable ref.Exp. valve hissesPuge & charge
2.  Clogged strainerTemp. change in ref. lineReplace
3.  Ice or dirt on evaporatorReduced air flowClean
4.  Exp. valve stuckSuperheat too highRepair / replace
5.  Improper superheat Short cycle/run continuouslyAdjust for superheat
6.  Clogged air filtersIce formation on evaporatorClean or replace


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