Condo Warm: Outdoor Unit's Air Path Blocked by Hoarding
A two-year-old system stops keeping up and an upgrade is proposed. A unit does not outgrow its room, so something else changed.
By Team Snowflake | Updated 24 Aug 2026
How this presents
One bedroom that used to cool normally now running at high fan constantly without reaching its set point, while the rest of the home is unaffected. Nothing indoors has changed. A construction project started nearby a few months earlier.
- Setup
- Mitsubishi Electric Wall-mounted4-6 yearsCondoKallang
- Misread as
- An undersized or faulty unit at two years old, and an upgrade to pay for.
- Check first
- What changed outside the building, once the indoor half reads normal
What else produces this
One room failing while the others hold puts the fault on that room's equipment or its air path, not on the system as a whole. Indoors is quick to clear: filter, coil, airflow at the grille, refrigerant. When all of that reads normal on a two-year-old unit, the remaining variable is the outdoor half, and the outdoor half can be obstructed by things that are not on the property.
A clean filter and coil with normal airflow measured at the grille clears the indoor half quickly.
Refrigerant and coil temperature reading normal for the rated size removes the charge from the question.
Fan speed at the control matching the motor's measured output rules out a failing fan.
Site hoarding erected directly facing that side of the building is a change nobody indoors would notice.
Why it happens
A condenser needs a volume of air moving past it, and that volume depends on what surrounds the building as much as what sits on the ledge. A hoarding panel raised close to one face reduces the air available to everything on that side. The equipment is unchanged and correctly sized. What changed is the supply of air, and it changed outside the boundary of anything the resident owns.
What resolution involves
Nothing on the unit, because nothing on the unit is wrong. What the resident needs is the finding in writing to take to building management, since the obstruction belongs to a third party and the remedy is a conversation rather than a part. Declining the upgrade matters as much as naming the cause: a larger unit in the same starved air path performs worse, not better, and costs more to run while doing it.
How to tell it worked
Performance returning when the obstruction does, which is the only proof available here. Until then the useful record is the date the hoarding went up set against the date the cooling changed.
Before you approve a quote
A unit does not outgrow its room
- Capacity is fixed at install. A system that used to cool a room has not shrunk since.
- Ask what changed outside before agreeing to a bigger unit. The condenser's air supply is not on your property.
- A larger unit in a starved air path performs worse and costs more to run than the one already there.
Questions this case answers
Is a near-new aircon that runs constantly undersized?
Does construction hoarding outside really affect cooling indoors?
Should I look outside before agreeing to a bigger unit?
Is there a way to rule out low refrigerant in a case like this?
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.