Symptoms
- Air blows but room stays warm
- Cools briefly then stops helping
- Unit runs constantly
- Hot air smell near the hose connection
Likely causes
- CommonExhaust hose disconnected, kinked, or poorly sealed at the windowHot exhaust air leaking back into the room cancels out the cooling.
- CommonFull internal water tank triggering a safety shutoffMany portable units stop cooling (or shut off) once the internal reservoir is full.
- CommonDirty air filterRestricts airflow across the coil, reducing cooling capacity.
- PossibleRoom too large for the unit's BTU ratingPortable units lose more capacity to hose length and heat than window units of the same rating.
- Less commonLow refrigerant from a leakAirflow is normal but the air is barely cool.
What to do
- Check that the exhaust hose is fully connected at both the unit and the window kit, with no kinks, tears, or gaps letting hot air leak into the room.
- Keep the hose as short and straight as possible; avoid stretching it or adding extensions.
- Drain or empty the internal water tank per the manual, or connect a continuous drain hose if the unit supports it.
- Remove and clean the air filter with warm water, then let it dry fully before reinstalling.
- Close the room off from adjoining spaces and seal gaps around the window kit with the included foam.
- Confirm the unit's BTU rating is adequate for the room's square footage, keeping in mind portable units generally need a higher rating than window units for the same space.
- If airflow and hose setup are fine but the air still isn't cool, the unit may be low on refrigerant.
Tools and parts
- None
Portable AC exhaust hoseSearch: “portable air conditioner exhaust hose replacement”
When to call a pro
Call an appliance technician if hose setup, drainage, and filter cleaning don't restore cooling, since a refrigerant leak needs professional service.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.