E439 on a Samsung heat pump: Refrigerant Leakage Error (Detect when the system is not operated)
Short answer
On a Samsung heat pump, E439 means: Refrigerant Leakage Error (Detect when the system is not operated). 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 · 3 sources
What it means
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
The manual says: Refrigerant Leakage Error (Detect when the system is not operated).
Part involved: Refrigerant circuit.
When it shows: Unit self-diagnosis: Refrigerant Leakage Error (Detect when the system is not operated).
Likely causes:
- Refrigerant leakage/shortage detected, or service valve closed, sensor fault or installation error.
- Engineer checks per Samsung service manual: Check refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors.
On the EHS Mono (R410A, AE***JXYD*H)
The manual says: Gas leakage error (Stop state).
Part involved: Refrigerant circuit.
When it shows: Unit self-diagnosis: Gas leakage error (Stop state).
Likely causes:
- Refrigerant leakage/shortage detected, or service valve closed, sensor fault or installation error.
- Engineer checks per Samsung service manual: Check refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors.
On the EHS TDM Plus (R410A)
The manual says: Error due to refrigerant leakage.
Part involved: Refrigerant circuit.
When it shows: Unit self-diagnosis: Error due to refrigerant leakage.
Likely causes:
- Refrigerant leakage/shortage detected, or service valve closed, sensor fault or installation error.
- Engineer checks per Samsung service manual: Check refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors.
Is it safe?
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: unknown.
What you can check
On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)
- Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; switch off at the isolator and keep ignition sources away from the outdoor unit; do not touch refrigerant pipework; then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.
On the EHS Mono (R410A, AE***JXYD*H)
- Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; leave the unit switched off at the isolator if advised; do not touch refrigerant pipework; then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.
On the EHS TDM Plus (R410A)
- Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; leave the unit switched off at the isolator if advised; do not touch refrigerant pipework; 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 refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: F-gas certified refrigeration/heat pump engineer; R290 (A3 flammable refrigerant) competence.
Certification: F-gas certification (UK F-gas Regulation; e.g. City & Guilds 2079 Cat I); R290/flammable refrigerant handling training (e.g. hydrocarbon refrigerant course).
On the EHS Mono (R410A, AE***JXYD*H)
- Check refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: F-gas certified refrigeration/heat pump engineer.
Certification: F-gas certification (UK F-gas Regulation; e.g. City & Guilds 2079 Cat I).
On the EHS TDM Plus (R410A)
- Check refrigerant leakage and shortage; check disconnection or breakdown of high and low pressure sensors. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.
Who to ask for: F-gas certified refrigeration/heat pump engineer.
Certification: F-gas certification (UK F-gas Regulation; e.g. City & Guilds 2079 Cat I).
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Insufficient heating (house not warm enough) on the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K): 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
- Samsung EHS Mono (R410A) Outdoor Unit + Control Kit MIM-E03AN Service Manual ↗ · EHS Mono + MIM-E03AN service manual · page ManualsLib viewer p.45 (printed p.44) · Reviewed 23 September 2026
- Samsung EHS TDM Plus Service Manual Code AC-07002A_0 (Feb 2017) ↗ · AC-07002A_0 · page p.66 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026