Chillin' Checks — Water Coming From Outdoor Split

Noticed water dripping from your outdoor air conditioning unit? It's one of the most common questions we get — and the answer is: it depends. Some water is completely normal. Other water can be a sign of a problem that needs attention. In this Chillin' Checks episode, we walk you through how to tell the difference.

When Water Is Normal

During cooling mode, your split system removes humidity from the air inside your home. That moisture (condensate) is drained away through the indoor unit's condensate drain line — which typically exits near or at the outdoor unit. A slow, steady drip of water from the base of the outdoor unit during operation is usually just this condensate draining away, and is completely normal.

In humid Queensland conditions, this can be quite a significant drip, especially when the system has been running hard on a hot day. You may also notice steam or mist from the outdoor unit in winter when the system runs a defrost cycle in heating mode — this is also normal.

When to Be Concerned

If the water is excessive, appearing from unusual locations on the unit, or accompanied by symptoms like reduced cooling performance, ice on the refrigerant lines, or unusual noises, it's worth investigating further.

Common Causes of Excessive Water

• ●Blocked condensate drain — the most common cause. The indoor unit's drain line can become blocked with algae, mould, or debris, causing water to back up and overflow.
• ●Low refrigerant — if the system is undercharged, the indoor coil can freeze and then defrost, releasing large amounts of water.
• ●Dirty indoor coil or filter — restricted airflow causes the coil to run too cold, leading to icing and subsequent water release when it defrosts.
• ●Incorrect installation angle — the indoor unit must be installed level or with a very slight pitch toward the drain outlet to allow condensate to flow correctly.
• ●Cracked or disconnected drain pan — the plastic drain pan under the indoor coil can crack or come loose over time.

What to Check First

The first thing to check is your air filter. A dirty filter restricts airflow over the indoor coil, which is the most common cause of icing and excessive water. If you haven't cleaned your filter in the last 4–6 weeks, start there.

If the filter is clean and the problem persists, turn the system off and call a licensed air conditioning technician. Refrigerant work must be carried out by a technician holding a current ARC Refrigerant Handling Licence — handling refrigerants without a licence is illegal under the Ozone Protection and Synthetic Greenhouse Gas Management Act 1989 and can result in significant fines.