How Do You Stop A Leak In A Ductless Air Conditioning System's Indoor Air Handler?

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Ductless mini-split air conditioners are a reliable, energy-efficient way to cool individual rooms in your home. They're dependable and rarely encounter mechanical issues. One problem that's commonly encountered with ductless mini-split systems, however, is water leaking from the indoor unit. Thankfully, this problem is easy to fix.

In almost all cases, a leaky indoor unit is caused by a clogged drain pipe. While the unit is in operation, the evaporator coils inside the indoor unit become much colder than the surrounding air. This causes condensation to form on the coils, which then leaks down onto a drain pan. From there, it enters a drain pipe that takes it outside of your home. When this drain pipe is clogged, the condensate simply builds up in the drain pan until it overflows, causing it to leak out of the unit.

In order to fix the problem, you'll have to clean your drain pipe. To do this, all you need is a screwdriver and some electrical tape. To find out what you need to do to remove the clog in your indoor unit, read on.

1. Turn Off the Power

For your safety, you'll first need to cut off the power to your ductless mini-split air conditioner from your electrical panel.

2. Remove the Indoor Unit's Case

In order to access the drain pipe, you'll need to remove the case on the indoor unit. Unscrew the retaining screws in order to remove it. If you can't find out where the screws are located, consult your owner's manual.

3. Locate the Drain Pipe

You'll see two pipes inside the indoor unit. These pipes run between the indoor air handler and the outdoor condenser unit. The smaller pipe (usually made of copper) is the refrigerant pipe; the larger one is the drain pipe. You'll notice that the drain pipe has two sections that are joined by electrical tape.

4. Disconnect the Drain Pipe

Place a bucket or a few towels underneath the indoor air handler, and then disconnect the two sections of drain pipe by removing the electrical tape. If the drain pipe is clogged then water will likely run out of the ends of both sections, so be prepared to catch it in your bucket or make sure it lands on your towels.

5. Remove the Clog and Take Preventative Measures to Keep It From Returning

The easiest way to dislodge the clog is to suction it out using a wet/dry vacuum. You'll need to make sure both sections of the drain pipe are unclogged. If you don't have a suitable vacuum, you can use a wire coat hanger to scrape out the clog.

At this point, you'll find out what caused the clog. If the clog is a tan color, it was likely caused by dust accumulating on your evaporator coils. The dust mixes with the condensate, drips into the drain pan, and clogs the drain pipe. Changing the air filter in your indoor unit more often can help prevent these types of clogs from returning.

If the clog is green, however, then it was caused by algae buildup. This is a common source of drain pipe clogs in humid conditions. Algae create a layer of biofilm on the drain pipe that prevent water from passing through. To prevent algae from coming back, add some copper sulfate to the drain pan—it rapidly kills algae. Condensate will eventually wash the copper sulfate away, so you'll need to periodically add more to prevent algae from building up in your drain pipe again.

6. Connect the Drain Pipe Sections and Attach the Case

Reattach the two sections of the drain pipe by wrapping them together with your electrical tape. Make sure the drain pipe is angled at a straight-downward slope away from the drain pan so that condensate correctly drains from your indoor unit. After reattaching the indoor unit's case, you're done with the repair.

If this repair doesn't fix the leak, the problem may lie in your refrigerant line instead of in the drain pipe. The refrigerant line is typically insulated to prevent condensation from collecting on it, but this insulation can eventually become detached. Condensation from the refrigeration line doesn't drip into the drain pan -- unfortunately, it drips onto your floor instead.

In order to fix the refrigerant line, you'll need to call a professional HVAC repair service. In some cases, the technician may be able to re-insulate the refrigerant line in order to prevent condensation from collecting on it. Have your indoor unit inspected by an HVAC contractor in order to determine if the refrigerant line can be repaired and the leak finally stopped.

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15 October 2019