Cleaning Air Handler and Air Handler Drain Lines


The most important reasons for cleaning air handler units and drain lines is the dirt, dust, and clogs that collect inside them. Even in large industrial units with two or more drain lines, the normal flow from the condensate is insufficient to flush out the lines. Due to this, it’s essential to make sure that the air handler units and their drain lines are cleaned periodically.

If you are responsible for maintenance of the unit and don't want to spend money hiring an outside professional, here are some tips that you will hopefully find useful in clearing your unit's drain lines.

Disconnect the Air Handler Unit

The sections of the air handler should be disassembled step by step, only to the extent necessary to expose the drain lines. Of course, while there, it's a good idea to clean coils, fins, and fan, too.

  • First of all shut down the HVAC system, and turn the power off at the source.
  • Now, disconnect the air handler drain lines.
  • After this, remove fan and coils of the air handler from their places, carefully.

How to Clean Air Handler Coils, Casing, and Fan

The coil and fan require the same procedure to clean properly, and the steps are given below.

  • First, you should clean out any dust and dirt present inside the air handler casing. A shop vac can make this easy.
  • To clean coils and fan, use an antimicrobial solution. When the solution turns the coils and fan white, use a garden hose to remove the dirt.

Clean air handler coils

How to Clean the Air Handler Drain Lines

You can clean the drain lines three easy ways.

1- After disconnecting the drain lines, you can use the jet of water from the garden hose. This method will probably only be helpful in the event of minor clogging.

2- You can use a sewer tape or a hand spinner for better cleaning. You only need to make some effort by simply inserting it into the drain line, and following it down until it removes the entire clog inside them. Furthermore, you could first try running the tape from the outside of the drain line.

3- Some people prefer to use their shop vac to clean drain lines. For using shop vac, you will need to fix the vacuum hose on the exit point of the drain line, and use binding tape to fix it properly. After this, start the vacuum, and keep it on up to fifteen minutes. The vacuum will suck the entire clog present inside the line out, and finally, you will get the line properly cleaned.

Pour the Bleach

After cleaning, it's a good idea to pour household bleach into the drain lines from the air handler. This will retard the rate of collection of a new clog.

Mounting a UV light in the air handling unit is another good idea to prevent clogs. You can use this lamp on the downstream side of all cooling coils and above the drain pan. UV also restricts microbial action that may lead to future clogs.

After cleaning air handler drain lines, assemble all parts of the air handler again.


  • Disconnecting and connecting the drain lines should be done carefully so as to avoid any major damage.
  • To keep the drain lines clean, it’s important to change the air filters periodically, say, after a month.
  • When you change the air filters, pour the household bleach, about ¼ cup, into the drain lines; it would save your money and effort both.
  • After cleaning, let them dry before pouring the bleach.


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