Troubleshooting a ductless mini-split
The mini-split is on, but the room stays cold.
Most ductless problems start at the remote or the filters. Check those before anything else.
Before you call anyone
A cold room: check, understand, then call
Each indoor head has its own filters and its own settings, so check the one in the cold room first.
Safe to check yourself
Check these first
From Trane's advice to owners.
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Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
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Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
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Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
Worth a visit from us
What it usually means
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Low refrigerant
From a leak, a wrong charge or a poor installation.
What we do: We leak-test the lines and fix the cause before we recharge.
Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
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A frozen indoor coil
Dirty filters, a dirty coil or a leak can freeze it, and it stops heating or cooling the room.
What we do: We clean the coil and find what froze it.
Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
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A part wearing out
The older the system, the more likely a compressor, sensor or board has failed.
What we do: We test it and tell you what failed before we replace anything.
Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
Stop, and call
Who to call first
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If it was just installed, call the installer
A new system that won't heat goes back to the company that put it in. If that was us, call us.
Source: Trane, Why Is My Mini-Split Not Working in Heat Mode?, checked 2026-10-22.
Tell us what it's doing. We'll take it from there.
Call and describe the problem: the noise, the smell, the room that never warms up. Or book a visit online.
