Using Mysa for Low Voltage with Moovair Mini-Splits via a 24 V Interface Kit

Last updated: November 11, 2026

Audience: Support/installer reference. Use this when a customer is trying to use Mysa for Low Voltage with a Moovair/Midea-style mini-split or heat pump through an OEM 24 V thermostat interface kit.

What we learned

Mysa for Low Voltage can work with a mini-split/heat pump only when the system has a proper OEM 24 V thermostat interface module installed. The interface module must convert the indoor unit controls into standard low-voltage thermostat terminals that Mysa LV can control.

In the Moovair Meridian example, the customer had already installed a 24 V interface kit and 240 V to 24 V transformer. The remaining issue was not whether Mysa LV could be used in principle, but how the interface kit was configured and which Mysa HVAC configuration code matched that setup.

Before recommending Mysa LV for a mini-split

  • Confirm the customer is using Mysa for Low Voltage, not Mysa for Mini-Splits.

  • Confirm the mini-split/heat pump has an OEM 24 V thermostat interface module installed or available from the equipment manufacturer/supplier.

  • Confirm the interface provides standard thermostat terminals such as R/Rc/Rh, C, Y/Y1, G, O/B, and optionally W2/AUX or E.

  • Have the installer confirm whether the interface board is configured for heat pump logic or conventional thermostat logic.

Recommended troubleshooting path

1. Confirm the 24 V interface kit wiring

For a 1-stage heat pump without auxiliary heat, the common wiring expected is:

  • Rc/Rh or R — 24 V power

  • C — common

  • Y1 — compressor call

  • G — fan call

  • O/B — reversing valve

If auxiliary or emergency heat is installed, the installer should also verify the corresponding W2/AUX and/or E terminals on the interface board.

2. Verify reversing valve logic

If the customer’s current Mysa HVAC code does not work, the most likely mismatch may be the reversing valve setting:

  • O = reversing valve energized in cooling

  • B = reversing valve energized in heating

For Moovair/Midea-style 24 V interface kits, installers may need to test whether the board expects B logic instead of O logic.

3. Try the appropriate Mysa HVAC configuration code

If the system is a 1-stage heat pump with no auxiliary heat, and the current code is not working, try:

  • 31J — 1-stage heat pump, no auxiliary heat, reversing valve energized in heat/B. Recommended first test when 31N does not work.

If auxiliary electric heat is present, use the matching auxiliary heat configuration instead:

  • 31P — heat pump with auxiliary heat, reversing valve energized in cool/O.

  • 31L — heat pump with auxiliary heat, reversing valve energized in heat/B.

If the interface board is configured to accept conventional thermostat calls instead of heat pump calls, the installer may need to use a conventional configuration such as:

  • 11B or 21B — use only if the interface board is set up for conventional 1 heat / 1 cool control rather than heat pump logic.

4. Allow the system time to respond

After changing the HVAC configuration code in the Mysa app, wait 5–10 minutes before concluding the code failed. Mini-split inverter boards and interface modules may have a delay before responding to new calls.

Suggested support guidance

If a customer asks whether Mysa LV can be used with a mini-split:

Mysa for Low Voltage is not designed to connect directly to a mini-split’s proprietary communication terminals. However, if the manufacturer provides an OEM 24 V thermostat interface module that converts the system to standard low-voltage thermostat terminals, Mysa LV may be used through that interface. The installer will need to confirm the interface wiring, whether the board is configured for heat pump or conventional logic, and whether the reversing valve uses O or B logic.

Example: Moovair Meridian

For a Moovair Meridian mini-split/heat pump with a 24 V interface kit installed:

  • If the customer is using code 31N and the system does not respond, try 31J first to test B reversing valve logic.

  • If auxiliary heat is connected, verify W2/AUX wiring and use the matching auxiliary heat code.

  • If the interface board is configured for conventional thermostat signals, use the appropriate conventional 1H/1C code instead of a heat pump code.

Notes / cautions

  • Do not recommend connecting Mysa LV directly to proprietary mini-split communication terminals.

  • Always defer wiring changes to a qualified HVAC installer/electrician.

  • Confirm the exact OEM interface module documentation whenever possible, as terminal behavior can vary by manufacturer and board configuration.

  • If the customer has Mysa for Mini-Splits installed instead, follow the IR remote-code pairing troubleshooting path instead of LV wiring guidance.