Causes When Mini Split Not Blowing Cold Air

By | May 30, 2022

Causes When Mini Split Not Blowing Cold Air
If you have a mini split that is no longer blowing out cold air, there can be several causes and fixes.

Mini split units are usually very reliable and last many years for cooling and heating space.

As with anything, there can be issues at times with the problem needs to be narrowed down.

The first thing to do with any mini split unit not cooling is to see if it has any error codes that point to the issue.

If the inside unit has an error code, the code can be looked up in the manual or online to see what part of the system has failed.

Sometimes no error code displays, but the system is not working correctly, in which case more troubleshooting will need to be done.

Most Common Causes When Mini Split Not Blowing Cold Air

  • Temperature not Set Correctly or not Set on Cool
  • Temperature not Set Correctly or not Set on Cool
    A common problem is the unit is not set to a low enough temperature or not set on cooling mode.

    The remote control usually sets the temperature and heating or cooling mode.

    Each system works differently but be sure to check it is set to cool and set to a low temperature so the unit will startup.

  • Line Set Leak

  • The line set is two copper lines that run between the indoor and outdoor units which carry refrigerant.

    The refrigerant cycle through the system carries heat away or in, depending on the mode.

    If the system has a leak, the refrigerant will become low, and the unit will no longer work properly.

  • Low on Refrigerant
  • A system low on refrigerant will not send out cool air.

    This is usually caused by the issue above with the leaky line set.

    While the line set is the, usually cause the indoor or outdoor unit can also leak and be an issue.

    If the system is low on refrigerant it will need the correct amount added back in which is done by weight.

  • Indoor Unit Dirty or Clogged
  • Indoor Unit Dirty Clogged
    The inside unit can become clogged with dirt and debris, which will stop them from working.

    There are usually two filters that filter out any contaminants which can be checked to see if they are clogged up.

    In some cases, the inside condenser can become clogged up with debris and need a full cleaning.

  • Communication Line Wiring
  • The communication wires run between the inside unit and the outside unit.

    There are usually 5-7 wires which allow the two units to communicate and bring in power for the indoor unit.

    If one of the connections is bad, the system will have a problem with usually sending out an error code.

    While the main PCB usually sends out an error, a faulty communication wire can cause strange issues with no codes at times.

  • AC Electrical
  • The unit, of course, needs power to operate, and the AC electrical should be checked.

    The breaker and disconnect can be checked to be sure they are working correctly.

    A multi-meter can also be used to measure the power at the outside unit terminal leads where the power goes into the unit.

  • Fault Indoor Unit
  • The indoor unit may be having issues and should be checked.

    The main indoor components are the blower motor, wiring, clogged condenser, or leaky unit.

  • Faulty Outside Condenser
  • The outdoor condenser should also be checked for any issues.

    The condensing fan motor can be tested and checked to see if it is spinning.

    An outdoor unit also contains the compressor and PCB boards.

Summary
Having a mini split that stops blowing cold air can no doubt be very annoying, especially on a hot day.

Common issues include the unit not set on cooling mode, Leaking refrigerant, low refrigerant, clogged indoor unit, and more.

Often an error code is displayed on a unit when it stops cooling, but in some cases, no code displays.

If a code does display, it will help to point to the problem and the bad component.

Each part of the mini split will need to be examined for what the potential cause and fix will be.

While mini split units are not as big as traditional HVAC units, they still work the same with refrigerants and different pressures flowing through a closed system.

Have you had issues with a mini split not cooling? Let us know in the comments below.

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