Mitsubishi Mini-Split Not Heating: Causes and Fixes
Quick Answer
Mitsubishi mini-split not heating in cold weather: Mitsubishi's Hyper-Heating (H2i) technology is designed to produce heat down to -13F, but standard Mitsubishi models lose significant heating capacity below 20F. Check your model: MSZ-FH (Hyper-Heat) vs MSZ-GL (standard). In heating mode, the outdoor unit extracts heat from outdoor air.
Mitsubishi mini-split not heating in cold weather: Mitsubishi's Hyper-Heating (H2i) technology is designed to produce heat down to -13F, but standard Mitsubishi models lose significant heating capacity below 20F. Check your model: MSZ-FH (Hyper-Heat) vs MSZ-GL (standard). In heating mode, the outdoor unit extracts heat from outdoor air. Below the rated minimum, the compressor cannot generate enough pressure differential. The outdoor coil will ice over - defrost cycles run every 30-90 minutes (indoor unit pauses heating during defrost, this is normal). If the outdoor coil is completely encased in ice and defrost is not clearing it, the defrost thermistor has failed.
What Does the NOT-HEATING Code Mean?
Mitsubishi mini-split not heating: see brand-specific guide above.
Most Likely Causes
Based on aggregated repair data, here is the probability breakdown for this error code:
Symptoms You May Notice
- Mitsubishi Mini-Split Not Heating symptom
Can you reset a Mitsubishi minisplit to clear the NOT-HEATING code?
Unplug 60 seconds.
Tools Required for Diagnosis
Diagnostic Checklist
Follow these steps in order. We start with the easiest external fixes before opening up the machine.
Follow brand-specific diagnosis above.
Follow brand-specific diagnosis above.
Check error codes and secondary causes.
Professional diagnosis if basic checks fail.
Frequently Asked Questions
Mitsubishi minisplit repair cost?
Repair or replace?
DIY?
Last verified for technical accuracy on March 15, 2026