Aircon Wall Unit Leak, Blocked Drain Tray

Case Details

What We Checked

• No visible cracks or deformation on the housing — seams were intact and clips seated correctly.
• Drain tray had a thick layer of compacted dust mixed with biofilm covering the outlet.
• The blockage caused condensate to back up and spill forward over the tray lip.
• Drain pipe itself was clear downstream — the restriction was only at the tray outlet.

The Diagnosis

The drain tray outlet had narrowed to almost nothing. Dust from the office environment had mixed with moisture to form a biofilm layer across the tray. Condensate backed up behind it and overflowed. The housing was structurally fine.

What Fixed It

We cleared the biofilm from the tray, flushed the outlet, and tested drainage by running the unit at full cooling. Water flowed cleanly to the drain pipe with no overflow.

Dripping stopped on the same visit. The unit ran normally for the rest of the afternoon with no water on the floor. No parts were replaced and no unit swap was needed.

Why This Happens

Drain tray blockage vs cracked housing.

• Water dripping from the front of the unit usually means the drain tray is overflowing, not that the housing has cracked. Cracked housings are rare on units under ten years old.
• Dust and biofilm build up in the tray over time, especially in office environments where the unit runs long hours. The blockage forms at the tray outlet where it narrows.
• A clogged tray is cleared by flushing the outlet and wiping down the tray surface. It does not require parts or unit replacement.