Troubleshooting Guide

For AC Cooling Units

Initial Check: 

  • Check Temperature in enclosure / Ambient around enclosure
  • Is there power to the AC unit?  What is voltage?
  • Check for door contact or jumper at logic pins 3-4
  • What is running? Internal fan, External fan, Compressor
  • What is the condition of the ambient air? Dirt, humidity, etc
  • What is the state of the LED? Solid is normal condition

 

  Incoming Failure Information

Questionnaire for Failure Identification

Remarks

1. AC unit not working

  • Compressor not working
  • Fans not working
  • Operating light OFF/ flashing
  • Mains supply connected, Y/N
  • Back up fuse
  • Not installed/ Faulty
  • Door contact open
  • Cabinet door open/ Bridge not set

 

2. AC unit not cooling

  • Internal fan working

 

  • Temperature setting too high
  • Lack of refrigerant
  • Oil marks inside the unit found
  • Th.-Exp.-valve iced up
  • External fan not working
  • Compressor not working
  • Condenser fouling

 

3. Cabinet temperature high

  • Temperature setting too high
  • Check parameter setting on the PCB, DIP-switch position
  • Internal fan not working
  • Compressor not working
  • External fan not working
  • Th.-Exp.-valve blocked
  • Th.-Exp.-valve, capillary tube broken
  • Unit capacity limits exceeded, too high dissipation heat
  • Ambient temperature exceeded maximum permitted temp. value
  • Shut down via HP-switch
  • No air T-difference via evaporator
  • Installation of E-components close to the cooled air outlet, i.e. cooled air short cut

 

4. Cabinet temperature low

  • Temperature setting too low
  • Check parameter setting on the PCB, DIP-switch position
  • Compressor working permanent
  • External fan working permanent
  • Unit capacity too big, too low dissipation heat
  • Ambient temperature exceeded minimum permitted temp. value
  • No air T- difference via evaporator
  • T-sensor broken

 

5. HP switch, Unit safety shut down

  • Condenser fouling extreme
  • External fan not working
  • External air inlet blocked
  • External air outlet blocked
  • High ambient temperature ambient temperature exceeded maximum permitted temp. value

 

6. Lack of refrigerant

  • Oil marks surrounding the refrigerant piping and or components
  • Low air T- increase over the condenser
  • Compressor power consumption low

 

7. Compressor not working

  • Shut down via high winding temp.
  • (Klixon)
  • Shut down via HP- switch
  • Compressor start relay defect
  • Compressor control relay defect
  • Compressor start capacitor defect
  • Short cut compressor winding

 

8. Fan not working, Internal/ External

  • Fan start capacitor broken
  • Fan mechanically defective

 

9. Condensate drain fails

  • Condensate drain clogged
  • Condensate hose is clogged
  • Condensate hose has no slope to drain to ambient

 

 

 

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