Working as a Heating Professional Can Lead to Success

Troubleshooting Your Mini-Split AC Unit

10 April 2015

Abbie Wade

A mini-split, or ductless, air conditioning system isn't prone to the same issues as a traditional central HVAC unit. Mini-split systems are often more durable and less likely to suffer problems, compared to the central types. This can make troubleshooting difficult for a homeowner unless you are aware of the most common issues with a mini-split system.

Issue: Fan Is Blowing, But the Air isn't Cool

There are two common causes for this issue that don't require a repairman. The first task is to turn off the unit and check the air filters. If the filters are dirty, simply clean or replace them. If the filters are fine, check the outdoor condenser unit. If you find ice buildup, turn off the unit and allow it to melt before turning the unit back on.

Although your unit will recover from icing, this does usually indicate another problem. You may be trying to cool a space that's either too large or too small for your system, or there could be a problem with the condenser or blower. Although it's not an emergency, you will want to schedule an HVAC inspection soon so you can find the root of the issue.

Issue: The Unit Fails to Turn On

Most mini-split units will show an error code on the central display or on the remote control, so your first task is to check for error codes. You can then cross-reference the code in your owner's manual or give it to your repair technician so they can quickly find and fix the problem.

If no code is given, you may have an electrical problem. If there is no readings showing on the displays, power is probably not reaching the unit. Check the breaker box for a tripped fuse before calling in the repair. If the unit is powered but there is no code given for guidance, you will need to call an HVAC technician to assess the unit.

Issue: The Unit Is Leaking

Mini-split units drain water, just like central and window units. The drainage occurs from the outdoor mounted compressor. At installation, the drainage hose should be installed so that it drains away from the unit and the house.

Check the drain hose regularly to make sure that it's working properly. Make sure that no leaves or vegetation blocks the drain hose or rests against the compressor.

Issue #4: The Controls Fail to Work

Most units are controlled by a remote controller or a wall-mounted wireless unit. The first step in troubleshooting these units is to check the battery power. If changing the battery doesn't work, it may be time to replace the controls. Your technician can help you check the wiring inside the units and secure a replacement, if necessary.

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