What is an AC drain line?
During the cooling process, your air conditioner removes water vapour from the air thus making your premises more comfortable. This water vapour condenses and needs to be removed from your air conditioner.
This is done by means of the drain line which is usually PVC pipe directed to a down pipe or waste point externally
Every ac system requires a condensate drain line.
Why do drain lines clog?

There are various causes as to why a drain line will block.
Lack of service to the HVAC system is a primary cause.
Dirty filters can permit debris to pass through the filter and pollute the cooling coil.
This debris can then get washed down into the drain pan.
Once sufficient debris is in the drain pan this can block the inlet to the condensate drain line.
it can also carry on down into the drain pipe and, over time, a build up can occur which causes a blockage.
In the case of a ducted system, lack of maintenance with regards to the p trap, if fitted, can also create drainage issues.
What are the symptoms of a clogged ac drain line?
In the case of a wall mount split system air conditioner, the indoor unit can start blowing excessive water from out of the front of the unit.
Condensate water can also run down the wall from behind the indoor unit
With a ducted air conditioner, there is normally a safe tray under the in ceiling indoor unit.
With a build up of water, this can lead to the safe tray filling. Checking of the safe tray outlet can warn of condensate problems.
On a ducted air conditioner, a trap may often be installed. This needs to be maintained to ensure correct condensate flow in the drain line.

A wet ceiling will also show that the condensate drain line is not operating correctly.
How can regular air conditioning maintenance help address a clogged drain line?
Your air conditioning unit should be serviced regularly. Apart from checking other system component and operation, the service will include checking your ac’s drain line. Regular servicing will ensure your filters remain clean and the indoor unit coil is clean and clear of debris.
Learn more about our air conditioning servicing & maintenance services.
Safety precautions you need to take before unclogging your drain line
Prior to attempting to clear the blocked drain line yourself, there are some safety precautions to adhere to, to ensure neither you nor your air conditioning unit suffer injury or damage.
Turn off the power
Adjacent to the outdoor unit, there is normally an electrical isolator. Turn this off prior to carrying out any work on your ac unit. If there is not an isolator there, locate the circuit break in your electrical board and turn this off.
Wear protective gear
If you will be using hot water or any product to attempt to clear the air conditioner drain line, ensure you wear the correct protective gear.
Step by step guide to unclogging the drain line
Some simple steps can be taken to attempt to unclog your ac drain line.
Step 1: Locate the Drain Line
With a wall mount ac unit, the drain runs from the drain pan in the unit then via the drain pipe to the waste point.The drain line from a ducted system normally will run from the in ceiling indoor unit, through the ceiling void then exit to the discharge point
Visually check the drain line to ensure there is no debris blocking it at the discharge point
Step 2: Check for Visible Clogs
Look in the drain pan to check if there is debris present at the outlet of the drain.
If so, clear the debris and check if the water flows away down the drain line.
Top tip: To ensure no further debris build up, ensure filters are cleaned on a regular basis
Step 3: Manually Remove Initial Blockages
Remove any debris from both the inlet and outlet points of the ac drain lines. Pour some water down the drain to see if it now flows.
Step 4: Use a Wet/Dry Vacuum
You can try a wet/dry vacuum clean from either end of the drain line. Ensure the hose from the vacuum is sealed into the drain pipe.
Step 5: Flush the Line with a Cleaning Solution
You can attempt to mix some cleaning solution with hot water and pour down the drain line.
Step 6: Rinse the Line with Water
If you have managed to clear the blockage, pour copious amounts of water down the drain to ensure all debris is cleared from the drain pipe.
Top tip: If you can see the drain outlet check that only clean water is coming out
Know when it’s time to call a professional
If none of the above works, it is time to call us. Our technicians are trained and proficient in the clearing of drains.
They will ensure your air conditioners have proper drainage.
They will also clear any excess water from the condensate pan and condensate line and to ensure the chance of future clogs are minimised
How to prevent the drain line from clogging in the first place
The key to ensuring minimal drain blockages is to make sure the filter and evaporator coil are kept clean.
Routine servicing by professionals in the best method for this.
Routine air conditioning servicing
With regular routine servicing, the following items are checked:
- Cleaning of filter
- Flushing the drain line pipe.
- Clearing of any standing water in drain pans
- Checking there is no debris build up in the indoor coil – clearing of any visible debris
Regular drain line cleaning
Regular drain line cleaning can alleviate the need for costly ac repair. Dirt and mould buildup is limited.
What causes recurring clogs in the AC drain line?
As per above, recurring drain line blockages are normally due to lack of routine maintenance.
Maintenance will keep the ac drain line clear of dirt and debris
How can I tell if a clog has been fully removed?
- Pouring large volumes of water into the drain line and watch it flow away rapidly is a positive sign that the blockage has been removed
- Checking the external discharge point for clear flow will also verify this.
How can Sun City Air Conditioning help me with a clogged drain line?
Our technicians are experienced in this type of work.
They will clean the filters and drain pan.
They will also advise if the coil is starting to accumulate debris and recommend a coil clean when required.