Mini-split not cooling or heating?

The indoor head runs but the room doesn't get cooler or warmer. The most common cause is dirty filters in the head. Check the filters, the remote's mode and the outdoor unit first; refrigerant and electrical parts are for a pro. A mini-split is a ductless heat pump, so the heat pump not heating and heat pump blowing cold air pages apply too.

Not sure which one it is? Snap your mini-split and we’ll narrow it down.

Is water dripping from the indoor head?

That's usually a clogged drain line, not a cooling fault. Mini-split leaking water

Likely causes

  1. Dirty filters in the indoor head

    Most commonEasy DIY

    Weak airflow from the head, dust visible on the filters when you open the front cover, or a room that cools or warms slowly.

  2. Remote mode, setpoint or batteries

    Most commonEasy DIY

    The remote's screen shows Dry or Fan instead of Cool or Heat, the set temperature is on the wrong side of the room temperature, or the screen is dim or blank.

  3. Outdoor unit blocked by snow, ice or leaves

    CommonEasy DIY

    Snow, ice or leaves packed around the outdoor unit, or an outdoor fan that isn't turning while the indoor head runs.

  4. Defrost cycle in heating mode

    CommonEasy DIY

    In heating mode the head stops blowing and the fans go quiet for a few minutes, then it resumes. That pause is normal and not a fault.

  5. Tripped breaker or an error code

    CommonModerate DIY

    The head is dead, or its lights are blinking in a pattern. The blink pattern is an error code: look it up in the manual. Check the breaker and the outdoor disconnect.

  6. Low refrigerant from a leak

    Less commonCall a pro

    Both the head and the outdoor unit run, but the air is only mildly cool or warm, there is ice on the indoor coil or the refrigerant lines, or it has been getting worse over time.

    Part: $200–1,500 (leak repair); $100–600 (recharge)

  7. Failed blower motor or circuit board

    Less commonCall a pro

    The head won't blow air, makes grinding noises, or shows an error code that comes back after a power reset.

    Part: $300–1,000 (blower motor); $150–700 (circuit board)

Quick checks

Switch off the breaker or the outdoor disconnect before cleaning anything beyond the filters. Don't chip ice off the outdoor unit; you can puncture the coil or refrigerant line. Refrigerant work needs a certified technician. If you smell burning or see smoke or sparks, switch the power off and call a pro.

  1. On the remote, set the mode to Cool or Heat (not Dry or Fan), set the temperature well past the room temperature, and replace the batteries if the screen is dim or blank.
  2. Open the front cover of the indoor head and look at the filters. If they're clogged with dust, clean or replace them following the manual.
  3. Look at the outdoor unit: clear leaves and loose debris from around it, and note any snow or ice.
  4. If it's heating and the head paused with the fans off, wait a few minutes: that's a defrost cycle.
  5. If the head's lights are blinking, note the pattern and look it up in the manual.
  6. Check the breaker for the head and the outdoor unit. Reset a tripped breaker once only.
Sharpen the read

Diagnose your mini-split in seconds, for free

No account, no phone number. Fixology’s AI reads your photo and tells you what’s likely wrong, how worried to be, and whether it’s a DIY fix.

Snap one of these:

  • the indoor head with the front cover open, showing the filters
  • the remote's screen
  • the outdoor unit

Add a note or more photos next. Nobody calls you.

When to call a pro

The room still isn't cooling or warming after the filter, remote and outdoor unit checks, an error code returns after a reset, the outdoor unit stays iced over, or you suspect a refrigerant leak. For upkeep, see the mini-split guide.

Typical cost: $100–1,500 for ductless mini-split repair. The service call runs $75–250 flat and often doubles as the diagnostic fee.

Sources: Fixr: How much does heat pump repair cost? (updated January 21, 2026)

After a scan, Fixology can also help you find pros near you.

Related problems

  • Mini-split leaking water?

    Mini-split

    Water drips from the indoor head, which is usually a clogged condensate drain line, a kinked hose, or a coil that froze and is thawing.

  • Furnace won't heat?

    FurnaceFall

    The furnace runs but the house stays cold, which is usually a clogged filter, a thermostat setting, or an ignition fault.

  • Heat pump not heating?

    Heat pumpFall

    The heat pump runs but the house stays cold, which is usually thermostat settings, a clogged filter, or an iced-over outdoor unit.

  • Washer won't drain?

    Washer

    Water is left in the drum after the cycle, which is usually a clogged pump filter or a kinked drain hose.

Fixology helps you understand your home — it isn't a substitute for a licensed pro on serious gas, electrical, or structural work.