E914 on a Samsung heat pump: Error due to Incorrect Thermostat Connection
Short answer
On a Samsung heat pump, E914 means: Error due to Incorrect Thermostat Connection. 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: Error due to Incorrect Thermostat Connection.
Part involved: Room thermostat input wiring.
When it shows: Unit self-diagnosis: Error due to Incorrect Thermostat Connection.
Likely causes:
- Room thermostat wiring fault: heating and cooling demand signals present at the same time.
- Engineer checks per Samsung service manual: Check wiring of hydro unit thermostat inputs (cooling/heating signals must not be concurrent).
On the EHS TDM Plus (R410A)
The manual says: Thermostat wrong connection error.
Part involved: Room thermostat input wiring.
When it shows: Unit self-diagnosis: Thermostat wrong connection error.
Likely causes:
- Room thermostat wiring fault: heating and cooling demand signals present at the same time.
- Engineer checks per Samsung service manual: Check wiring of hydro unit thermostat inputs (cooling/heating signals must not be concurrent).
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 thermostat/timer and controller operating-mode settings; then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.
What the engineer will check
- Check wiring of hydro unit thermostat inputs (cooling/heating signals must not be concurrent). Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: Heat pump engineer (controls).
Certification: Competent electrical worker (BS 7671).
What you might notice
What owners and engineers report
2 owner and engineer reports mention this.
- Controller / thermostat problem on the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K): 2 reports
Sources
- EHS R290 Mono Outdoor Unit Installation Manual AE***CXYD** (EU) DB68-12496A-03 ↗ · DB68-12496A-03 · page p.24 · Reviewed 23 September 2026
- Samsung EHS TDM Plus Service Manual Code AC-07002A_0 (Feb 2017) ↗ · AC-07002A_0 · page p.67 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026