Condo warm: outdoor unit's air path blocked by hoarding

A resident in a newer Kallang River condo noticed one bedroom staying warmer than the rest, even with the unit running constantly. A waterfront project was under construction two blocks away. Site hoarding placed close to a building can quietly restrict the outdoor unit's air path.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Mitsubishi Electric Wall-mounted2 years oldCondoKallang, Singapore

Concern: The resident worried the two-year-old unit was undersized or faulty and would need an upgrade.
Found: Outdoor unit's air path restricted by construction hoarding positioned close to the condenser intake and exhaust
Key check: Checked the building's exterior outdoor unit air path before assuming a sizing or refrigerant problem in a near-new unit
Result: The resident avoided an unnecessary sizing upgrade. Once management adjusted the hoarding gap, the room returned to its normal cooling time.

What we were told

The resident said one bedroom used to cool normally and now ran on high fan speed constantly without reaching the set temperature, while the rest of the unit cooled as expected. Nothing indoors had changed. A waterfront residential project had begun construction nearby a few months earlier.

What we checked

A two-year-old unit does not outgrow its room overnight, but a hoarding can choke its condenser in a week. Construction came first. The outdoor unit's air path can be restricted from outside the building entirely, without any visible change to the indoor unit or its filter.

The indoor unit's own filter and coil were clean, with normal airflow measured directly at the grille.
Site hoarding for the nearby waterfront project had been erected directly facing that side of the building.
Refrigerant levels and indoor coil temperature both read normal for the unit's rated size.
Fan speed at the control matched the motor's actual measured output, ruling out a failing fan motor.

What we found

The hoarding panel for the nearby construction site had been positioned close enough to partially block the air path that side of the building relied on. This reduced the volume of air the system could draw in and reject. The unit itself was working correctly, and was correctly sized for the room. It simply could not move enough air past an obstruction that sat outside the building entirely, never part of its original design, and never something the installer could have anticipated.

What fixed it

We flagged the hoarding placement to the resident to raise with building management. This was an external site condition, not a fault with the unit itself. No parts were replaced. No upsizing was recommended either, because the system tested correctly once the air path restriction was factored into the diagnosis.

Outcome

The resident avoided an unnecessary sizing upgrade. Once management adjusted the hoarding gap, the room returned to its normal cooling time.

What this case teaches us

A near-new unit running constantly can still be starved of air, not undersized

Nearby construction hoarding placed close to a building can quietly restrict an air path without anyone noticing from inside the unit.
A unit that runs constantly without reaching temperature is not automatically undersized. Check the outdoor air path before recommending a bigger system.
Ask whether anything has changed just outside the affected room's air intake, such as new hoarding or scaffolding, before approving sizing or refrigerant work.

Questions this case answers

Is a near-new aircon that runs constantly undersized?

Not automatically. This Kallang River unit was only a couple of years old, correctly sized for the room, and tested correctly throughout. Running constantly without reaching the set temperature means it cannot shed heat fast enough, and the reason for that can sit entirely outside the flat. Sizing was never the constraint here.

Does construction hoarding outside really affect cooling indoors?

It can. Site hoarding for a nearby waterfront project had been erected directly facing that side of the building, close enough to partly block the air path the outdoor unit relied on. That cut the volume of air the system could draw in and reject. Nothing indoors looked different, which is what made it confusing.

Should I look outside before agreeing to a bigger unit?

Always worth a look first. Ask whether anything has changed just outside that room, such as new hoarding or scaffolding, before anyone recommends a bigger system. Here the placement was flagged to the resident to raise with building management. No parts were replaced, and once the gap was adjusted the room returned to its normal cooling time.

Is there a way to rule out low refrigerant in a case like this?

Measure rather than guess. Refrigerant levels and indoor coil temperature both read normal for the unit's rated size at this condo. The filter and coil were clean, with normal airflow measured at the grille. Fan speed at the control also matched the motor's actual output, ruling out a failing fan. Attention then moved outside the building.

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.

WhatsApp us