E474 on a Samsung heat pump: [Inverter] IPM Heat Sink Error
Short answer
On a Samsung heat pump, E474 means: [Inverter] IPM Heat Sink Error. The heat pump stops until the fault clears or is reset. 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 EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
The manual says: [Inverter] IPM Heat Sink Error.
Part involved: Inverter PCB / compressor.
When it shows: Unit self-diagnosis: [Inverter] IPM Heat Sink Error.
Likely causes:
- Inverter/compressor drive fault: supply voltage issue, compressor wiring/winding, IPM/PFC/sensor fault on inverter PCB, refrigerant or airflow problem causing overcurrent/overheat.
- Engineer checks per Samsung service manual: Check heatsink assembly; exchange inverter PBA.
On the EHS Mono R32 (AE***RXYD*G)
The manual says: IPM(IGBT Module) or PFCM temperature sensor Error.
Part involved: Inverter PCB / compressor.
When it shows: Unit self-diagnosis: IPM(IGBT Module) or PFCM temperature sensor Error.
Likely causes:
- Inverter/compressor drive fault: supply voltage issue, compressor wiring/winding, IPM/PFC/sensor fault on inverter PCB, refrigerant or airflow problem causing overcurrent/overheat.
- Engineer checks per Samsung service manual: Check heatsink assembly; exchange inverter PBA.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
- Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; check the outdoor unit is not blocked by leaves, debris or snow and air can flow freely; then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.
What the engineer will check
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
- Check heatsink assembly; exchange inverter PBA. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: Heat pump engineer with electrical and refrigeration competence; R290 (A3 flammable refrigerant) competence.
Certification: Competent electrical worker (BS 7671); F-gas certification if refrigerant circuit is opened; R290/flammable refrigerant handling training (e.g. hydrocarbon refrigerant course).
On the EHS Mono R32 (AE***RXYD*G)
- Check heatsink assembly; exchange inverter PBA. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: Heat pump engineer with electrical and refrigeration competence.
Certification: Competent electrical worker (BS 7671); F-gas certification if refrigerant circuit is opened.
What you might notice
What owners and engineers report
9 owner and engineer reports mention this.
- No heating on the EHS Mono R32 (AE***RXYD*G): 6 reports
- Keeps stopping / cutting out on the EHS Mono R32 (AE***RXYD*G): 2 reports
- Intermittent fault on the EHS Mono R32 (AE***RXYD*G): 1 report
Sources
- EHS R290 Mono Outdoor Unit Installation Manual AE***CXYD** (EU) DB68-12496A-03 ↗ · DB68-12496A-03 · page p.24 · Reviewed 23 September 2026
- EHS R-32 Mono Outdoor Unit Installation Manual (EU) DB68-08408A-07 ↗ · DB68-08408A-07 · page p.44 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026