Common
Technician fixDamaged duct run to that room
One crushed, kinked or disconnected flex run starves one room while the rest of the house is fine. Attic storage, walkways and old repairs are the usual places.
Routine
One room won't cool down
When the rest of the house is comfortable but one room stays warm, the AC itself is usually fine, and the problem is getting air to that room. The common causes are a crushed, kinked or disconnected duct run, a run that's too small or too long for the room, no return path for air when the door is closed, or a room with more sun and glass than the duct layout accounted for.
- Florida-certifiedCAC1821225
- ServingBroward County · 14 cities
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Narrow it down first
These four comparisons narrow down where the problem is, for you and for the technician.
Done all of these and it’s still not right?
That points to a part that needs a technician’s meter, not another reset.
The path to one room
When the rest of the house is comfortable, the system itself is usually fine. The problem is on the way to that room, or on the way back from it.
Likely causes, most common first
Pick one to see how likely it is, who can deal with it, and what it means.
Duct repair
Common
Technician fixRun too small or too long
A room at the end of a long run, or one fed by a single small duct, may never get the air its heat load needs, especially on hot afternoons.
Occasional
You can check thisNo return path with the door closed
Supply air has to get back to the air handler. In a closed room without a return or transfer grille, air pressure builds and less air comes in.
Occasional
Technician fixHigher heat load than the design assumed
West-facing windows, a sunroom, a room over the garage or poor attic insulation over one area can need far more cooling than the room next door.
Occasional
You can check thisClosed or blocked register
A register closed by accident or covered by furniture or curtains cuts the airflow into the room.
Occasional
Technician fixLeaking duct joints on that branch
Air that leaks out at loose connections along the way never reaches the room.
How a room gets measured
The room is compared with the rest of the house, so the fix fits the actual shortfall.
°F
Compared with other rooms. Warm air at one register but not the others points to that run, which may be leaking or exposed to attic heat.
CFM
How much air the room actually gets, compared with what the room needs.
Sunny west windows, a bonus room over a garage or extra equipment can need more air than the original design gave it.
pressure
Shows whether the room can breathe out once the door is shut.
When to stop and call
Turn the system off and call a technician if:
- Water is dripping from the register or the ceiling around it. A sweating or disconnected duct can soak drywall.
- A musty smell or visible mold around the register.
- A burning smell from the vent.
What our visit looks like
A technician measures airflow and temperature at the room's register compared with others, inspects the run feeding it in the attic, and estimates what the room needs. The fix can be a repair to the run, a larger run, an added return or transfer grille, or a change to the duct layout.
If it turns out to be the ductwork
Planning a duct repair or replacement? See a rough range for the project in a couple of minutes, then we confirm it on site.
The on-site duct evaluation is free.
Questions
Do I need a bigger AC if one room won't cool?
Usually not. If the rest of the house is comfortable, the system has enough capacity, and the problem is delivering air to that room. A bigger system can make humidity worse. Fixing or resizing the duct run, adding a return path or reducing the room's heat gain is normally the answer.
Why is the room warmer when the door is closed?
Because the supply air has no easy way back to the return. Pressure builds in the closed room and less cool air comes in. A return grille, a transfer grille or a jumper duct gives the air a path back.
Talk to Service Shield
Florida license CAC1821225