| Exhaust hose or window kit missing | - Exhaust hose or window kit missing
| - Measure the exhaust outlet and note its shape and locking method.
- Look up the maker’s hose and window-kit part numbers for that model.
| - Rating label photo.
- Which parts are present: hose, unit-side adapter, window-side adapter, slider or seal.
| Basic Diagnosis time: Under an hour Low safety relevance | Fitting is simple. Finding the right part may not be: adapters are often proprietary, and a loosely fitting hose leaks hot air back into the room and spoils the result. | - Parts for that model are no longer sold.
- Unit cannot be tested for cooling.
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| Runs but cools poorly | - Dirty filters or coils
- Hot air not vented outside
- Unit too small for the room
- Refrigerant or compressor fault
| - Is the hose short, straight and vented outside, with the opening sealed?
- Are the filters and visible coil clean?
- Does the compressor start — a deeper hum and a change in the exhaust temperature — and stay on?
- Is the room a sensible size for the unit’s capacity?
| - How the seller used it: hose out of the window, or not.
- Whether it ever cooled well.
- How it was stored and transported.
| Basic to Professional, depending on the cause Diagnosis time: 1–3 hours Safety-critical | Cleaning and correct setup cost nothing. A refrigerant leak or compressor fault is sealed-system work, legally restricted to certified technicians in many countries, and it normally costs more than a used unit is worth. | - Compressor never starts, or starts and cuts out.
- Front air no colder than the room after fifteen minutes with everything set up correctly.
- Oily residue on the coils or pipes.
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| Leaks water or stops with “tank full” | - Blocked drain or full internal tank
- Stuck float switch
| - Drain the unit through its drain plug into a tray.
- Check the plug and any drain hose for cracks and the seal for being seated.
- See whether the “tank full” indicator clears after draining.
| - Where the water appears.
- Whether the unit was used in very humid conditions.
| Basic to Advanced, depending on the cause Diagnosis time: Under an hour Safety-relevant | Draining is owner maintenance. A float switch that stays stuck, or a failed condensate pump, means opening the unit. | - Water coming from the casing rather than the drain.
- “Tank full” that will not clear.
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| Fan not turning, thermal shutdown or tripping | - Fan motor or capacitor fault
- Refrigerant or compressor fault
| - Switch off and unplug. Look and listen only: does the fan try to turn, is there a burning smell, does the supply trip?
| - What happened just before it failed.
| Professional Diagnosis time: Under an hour Safety-critical | Fan motors and run capacitors are line-voltage components, and capacitors hold a charge after unplugging. This is work for a qualified person. | - Always, as a resale repair project.
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| Musty smell | - Mold inside the unit
- Dirty filters or coils
| - Remove and inspect the filters.
- Shine a flashlight at the coil and into the air outlet for visible mold.
- Drain it and smell the water.
| - How it was stored — drained and dry, or put away wet.
| Basic to Intermediate, depending on the cause Diagnosis time: Under an hour Safety-relevant | Filters and reachable surfaces can be cleaned as the manual says. Mold deep inside the unit cannot be reached without dismantling. | - Visible mold in the air path beyond what the manual’s cleaning reaches.
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