Fault Analysis Database
A/C Unit - DTS, DTI, DTT, DTD:
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 |
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1. AC unit not working
- Compressor not working
- Fans not working
- Operating light OFF/ flashing
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- Mains supply connected, Y/N
- Back up fuse
- Not installed/ Faulty
- Door contact open
- Cabinet door open/ Bridge not set
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2. AC unit not cooling
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- 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
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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
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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
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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
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6. Lack of refrigerant |
- Oil marks surrounding the refrigerant piping and or components
- Low air T- increase over the condenser
- Compressor power consumption low
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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
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8. Fan not working, Internal/ External |
- Fan start capacitor broken
- Fan mechanically defective
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9. Condensate drain fails |
- Condensate drain clogged
- Condensate hose is clogged
- Condensate hose has no slope to drain to ambient
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