Fault Analysis Database
Application Team Trouble Shooting
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 |
|---|
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
|
- 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
|
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| 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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