6 Intermittent Aircon Faults Worth Logging Before Service
An intermittent aircon fault is easier to test when its trigger is recorded before it disappears. Running time, rain, cooling load, indicator lights, sound and the affected-room pattern can each change the first inspection. The log preserves evidence; it does not diagnose the part.
By Team Snowflake | Updated 15 Sept 2026
Which details make an intermittent fault testable?
Record what happens just before the fault and what restores operation. For example: "E6 after three hours; clears after a rest." This gives the technician a load and recovery pattern to recreate.
Do not keep recreating a fault that involves a breaker trip, burning smell, water near electrical parts or visible sparking. Switch the system off and arrange the appropriate aircon or electrical inspection.
| Detail to log | Useful format | Test it can change |
|---|---|---|
| Running time | Started 7pm; E6 appeared after a long run; cleared after rest | Reproduce a heat- or load-dependent connection fault |
| Weather | Trips during rain; dry operation normal | Inspect weather-exposed power points and water paths |
| Load | Cuts out only in the hottest afternoon period | Check outdoor heat rejection and sustained-load behaviour |
| Light or code | Photograph the full code before resetting | Follow the correct manufacturer fault path |
| Sound | Click repeats with fan rotation and worsens in afternoon heat | Inspect rotating clearance before quoting a motor |
| Room pattern | Whole system stops only when one bedroom starts | Isolate the triggering indoor unit before testing shared parts |
- Detail to log
- Running time
- Useful format
- Started 7pm; E6 appeared after a long run; cleared after rest
- Test it can change
- Reproduce a heat- or load-dependent connection fault
- Detail to log
- Weather
- Useful format
- Trips during rain; dry operation normal
- Test it can change
- Inspect weather-exposed power points and water paths
- Detail to log
- Load
- Useful format
- Cuts out only in the hottest afternoon period
- Test it can change
- Check outdoor heat rejection and sustained-load behaviour
- Detail to log
- Light or code
- Useful format
- Photograph the full code before resetting
- Test it can change
- Follow the correct manufacturer fault path
- Detail to log
- Sound
- Useful format
- Click repeats with fan rotation and worsens in afternoon heat
- Test it can change
- Inspect rotating clearance before quoting a motor
- Detail to log
- Room pattern
- Useful format
- Whole system stops only when one bedroom starts
- Test it can change
- Isolate the triggering indoor unit before testing shared parts
Which six intermittent fault patterns are worth preserving?
These anonymised case patterns show why one recorded detail can move the inspection to a different part of the system.
1. Why should running time be logged?
Running time separates a fault present at start from one that appears after heat, vibration or condensation builds. Record both the start time and the first symptom.
A Yishun Mitsubishi showed E6 after running for hours, then cleared after a rest. Tracing the full cable route found a corroded signal-wire splice in a ceiling junction box that became unstable with thermal expansion.
2. Why should rain and recent weather be logged?
A fault that follows rain directs inspection towards exposed drainage, wiring and switch enclosures. It does not prove water entry, but dry-versus-wet behaviour is a strong test condition.
A Changi aircon tripped mainly on rainy evenings and ran normally in dry weather. Inspection under wet conditions reproduced the trip and found water entry in a rusted outdoor switch box.
3. Why should room load and time of day be logged?
Afternoon-only cutouts may follow outdoor heat or heavier simultaneous demand. Record which rooms were running and whether the outdoor unit was in direct sun or a restricted space.
An Ang Mo Kio LG cooled in the morning but cut out during the hottest afternoon period. A new structure above the outdoor unit trapped discharge air, and the cutout was reproduced during an afternoon inspection.
4. Why should the full light or error sequence be saved?
A photo or short video preserves the exact code, blinking sequence and unit that displayed it. Resetting first removes the clue a technician needs to choose the manufacturer test path.
In Bishan, an E6 error described as random aligned with each drain-pump cycle. Correlating the code timing with pump activation exposed interference from a pump cable run beside the communication cable.
5. Why should a changing sound be recorded?
Record whether the sound follows fan speed, compressor start, temperature or time of day. A sound pattern can separate rotating contact from an electrical start fault.
A Bukit Batok outdoor unit developed one click per fan rotation, worse in afternoon heat. Checking blade clearance found a slightly warped fan blade clipping the housing rather than a failed motor.
6. Why should the affected-room pattern be logged?
The room that triggers a shared failure can identify a local fault hidden inside a whole-system shutdown. Record which room started immediately before the event and whether the other rooms run without it.
A Buona Vista system 4 shut down only when one bedroom unit switched on. Isolating that indoor unit left the other three zones stable and narrowed the cause to its control board.
What is the shortest useful aircon fault log?
A compact log should preserve conditions, not a theory. One entry per event is enough.
| Field | What to record |
|---|---|
| Time | Start time, fault time and whether a rest or reset restored operation |
| Conditions | Rain, direct afternoon sun, recent cleaning or ceiling work |
| System state | Rooms running, set mode and which room failed first |
| Visible evidence | Code, blinking light, water location or normal-view photo |
| Sound or smell | When it starts and whether it changes with fan speed or load |
- Field
- Time
- What to record
- Start time, fault time and whether a rest or reset restored operation
- Field
- Conditions
- What to record
- Rain, direct afternoon sun, recent cleaning or ceiling work
- Field
- System state
- What to record
- Rooms running, set mode and which room failed first
- Field
- Visible evidence
- What to record
- Code, blinking light, water location or normal-view photo
- Field
- Sound or smell
- What to record
- When it starts and whether it changes with fan speed or load
What should not be done just to recreate the fault?
Do not repeatedly reset a breaker, bypass a drain switch, remove electrical covers or keep a unit running through a burning smell. An evidence log is not worth increasing the risk or damaging the system.
These six patterns only show how logged conditions changed specific inspections. Similar timing can come from different causes, so the final diagnosis still requires the relevant electrical, airflow, drainage, control or refrigerant test.
Common questions
What should be written down when a fault comes and goes?
How long should a unit be run to recreate an intermittent fault?
Why photograph the code before resetting anything?
Why does the room that fails first matter?
Sources
- FAQ
Mitsubishi Electric Asia · Checked
Give the error code and blink count when booking a service appointment.
- Daikin Room Air Conditioner Operation Manual (FTXM85P2VMA, FTXM95P2VMA)
Daikin Australia · Checked
Stop operation and cut the power if a burning smell or abnormality occurs.
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.