Heat pumps · Error codes · Midea
HdMidea
Hd on a Midea heat pump: Communication fault between master unit and slave unit
Short answer
On a Midea heat pump, Hd means: Communication fault between master unit and slave unit. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the M-Thermal Arctic HT R290 monobloc (MHC ...WD2N7)
The manual says: Communication fault between master unit and slave unit.
Likely causes:
- See R290 service manual troubleshooting (section 6) for this code.
On the M-Thermal Mono R32 (MHC ...W/D2N8-B / -B2 'Arctic')
The manual says: Communication fault between master unit and slave unit (in parallel).
Likely causes:
- SW9 DIP switch with wrong settings.
- More than two units are connected to the wire controller.
- Power-on interval between master unit and slave unit is longer than 2min.
- Wire connection error.
- Communication between units is unstable.
- Address code missing or address code setting duplicate.
- Main board fuse is damaged.
Is it safe?
On the M-Thermal Arctic HT R290 monobloc (MHC ...WD2N7)
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
On the M-Thermal Mono R32 (MHC ...W/D2N8-B / -B2 'Arctic')
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Read and note the exact code shown on the controller display.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- Restart once via the controller (OFF then ON) as the manual allows; if the code returns, call an engineer.
What the engineer will check
On the M-Thermal Arctic HT R290 monobloc (MHC ...WD2N7)
- See R290 service manual troubleshooting (section 6) for this code.
On the M-Thermal Mono R32 (MHC ...W/D2N8-B / -B2 'Arctic')
- SW9 DIP switch with wrong settings.
- More than two units are connected to the wire controller.
- Power-on interval between master unit and slave unit is longer than 2min.
- Wire connection error.
- Communication between units is unstable.
- Address code missing or address code setting duplicate.
- Main board fuse is damaged.
Sources
- R290 M thermal Arctic HT Series Service Manual ↗ · 2025-10-15 v5 (from file name) · page 91 · Reviewed 23 September 2026
- Midea M thermal Arctic Mono (4~16kW) Service Manual ↗ · not stated (MBT Confidential) · page 125 (table); 125 (troubleshooting) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026