The three most common reasons for water leakage from heat pumps are dirty filters or heat exchanging coils, blocked drains, and a shortage of refrigerant. They are pretty simple to diagnose and repair.
Remember: Turn off the power source to your air conditioner before trying any of the following!
1. Dirty Filters and or Blocked Heat Exchanger
When the filters, or heat exchanging coil, are dirty or blocked, this causes a restriction in air flow. This in turn can then cause the temperature of the coil to drop. If the coil temperature drops below zero, moisture in the air that is condensating on the coil can freeze and form little ice flakes which are then blown out of your air conditioner, causing water leakage.
Check the filters, and if they look dirty, give them a good clean with the hosepipe or shower head. Remove all the dirt and give them a spray with a kitchen or bathroom antiseptic spray to kill any bacteria or mould on them.
Check the aluminum coil behind the filters. If it is covered in dry lint, try vacuuming the coil carefully with the brush attachment on your vacuum cleaner. If it is particularly dirty, you will need to use a garden spray bottle and a strong grease removing kitchen cleaner. Spray it on the coil, allow to work for around 5 minutes then rinse the coil off with the spray bottle. This should remove the dirt and improve the air flow. Please be careful not to spray water near to the electrical panel on the air conditioner.
ALWAYS read the manufacturers’ manuals on how to clean your heat pump or air conditioner correctly!
2. Blocked Drains
On a wall mounted ductless air conditioner, a blocked drain can be pretty obvious and easy to diagnose. Water will usually drip down the wall from the back of the unit and may also leak through the air outlet at the front if the drain is blocked.
Stand on a small ladder and look down from the top of the air conditioner. Towards the bottom of the heat exchanger is a little plastic tray which is designed to catch the condensate produced by the cooling mode of the air conditioner. Check that this tray is not full of water or overflowing.
If your outdoor unit is directly behind the wall the indoor unit is mounted on, your drain pipe will likely follow the pipework through the wall and drip into the garden. If this is the case, find the end of the drain pipe outside, wipe the end clean with a cloth then blow as hard as you can into it. This should clear any blockages.
If you cannot clear the blockage yourself, or if it is buried inside the wall, you will need to phone a professional HVAC service company and book a service call.
3. Your Air Conditioner Has A Leak and Has Lost Refrigerant
If your air filters and heat exchanger are clean and you have lots of air flow, your air conditioner should deliver plenty of cool air. If it is struggling to cool the room for a few hours and then starts leaking water from the air vent it may be short on refrigerant.
Set your heat pump to the lowest setting possible and leave it to run for a little while. Then check the heat exchanging coil underneath the filters. If it is covered in ice, your air conditioner has a leak and requires a professional to service it. If your air conditioner is leaking refrigerant, the leak will need to be found and fixed before it can have additional refrigerant added to it.
If in doubt, or these tips don’t work, contact your local air conditioning company for a service.