Sanitising with a cover bag or by dismantling?

Updated 2026-09-04 · reviewed by certified technician

In short The collection cover is a double-layer waterproof sheet sealed around the indoor unit and ending in a drain hose; it allows pressure washing of the evaporator and blower right on the wall, with the dirty water collected and drained into a bucket. The studies that measured a >99% fungal reduction used exactly this combination: alkaline detergent, brushing and pressure washing.

A cleaning cover directs wash water to a container — The area and sensitive components are protected before work.
The cover collects wash water.
The hose directs water into a container.

Cover fitted on the unit, hose running neatly into the white bucket, spotless living room

What is really happening

The collection cover is a double-layer waterproof sheet sealed around the indoor unit and ending in a drain hose; it allows pressure washing of the evaporator and blower right on the wall, with the dirty water collected and drained into a bucket. The studies that measured a >99% fungal reduction used exactly this combination: alkaline detergent, brushing and pressure washing.

Dismantling makes sense only when the blower can no longer be cleaned in place (hardened deposits after years of neglect) or when the pan is cracked; otherwise it brings risks (broken clips, displaced sensors, cables) without a better result. We work with the cover on over 95% of units and say openly when dismantling is warranted.

The evidence

Before and after: what comes out of the unit

Inside of the indoor unit with the blower white and clean, after washing

BeforeAfter

Inside of the indoor unit with the blower black with deposits, before cleaning → Inside of the indoor unit with the blower white and clean, after washing

BeforeAfter

Grey, dust-laden filter on a white towel → White, clean filter on a white towel

BeforeAfter

Coil fins full of dust and fluff, before cleaning → Clean, silver coil fins after washing

BeforeAfter

Louver of the unit with black mould spots on the edge, before sanitising → White, clean louver after sanitising

Silver, clean coil seen through the cover after rinsing

BeforeAfter

Indoor coil black with deposits seen through the cover before washing → Silver, clean coil seen through the cover after rinsing

Washed filters left to dry on a white towel by the window

BeforeAfter

Open air conditioner with filters full of grey dust before cleaning → Washed filters left to dry on a white towel by the window

What to do

Mechanical pressure cleaning of the evaporator, blower and pan inside a collection cover, then sanitising; filters washed every two weeks; room humidity kept between 40 and 60%; the unit dried on fan mode before winter. No sprays over dirt, no bleach in the unit, no refrigerant "top-ups".

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