F3 on a Mitsubishi Electric heat pump: 63L connector open (low pressure switch connector circuit open)
Short answer
On a Mitsubishi Electric heat pump, F3 means: 63L connector open (low pressure switch connector circuit open). 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 · 8 sources
What it means
On the Ecodan Puhz Sw Split
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L working due to refrigerant leakage or defective parts; 4 Defective outdoor controller board.
On the Ecodan Puhz W Monobloc
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L working due to refrigerant leakage or defective parts; 4 Defective outdoor controller board.
On the Ecodan R290 Puz Wz
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L operating due to defective parts (refrigerant shortage); 4 Defective outdoor controller board.
On the Ecodan R32 Puz Wm
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L operating due to defective parts (refrigerant shortage); 4 Defective outdoor controller board.
On the Ecodan R32 Zubadan Puz Hwm
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L operating due to defective parts (refrigerant shortage); 4 Defective outdoor controller board.
On the Ecodan Ultra Quiet Puhz W Vaa
The manual says: 63L connector open (W112 only): low pressure switch 63L connector circuit open 3 minutes after power-on.
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L working due to refrigerant leakage or defective parts; 4 Defective outdoor controller board.
On the Ecodan Zubadan Puhz Hw Monobloc
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L working due to refrigerant leakage or defective parts; 4 Defective outdoor controller board.
On the Ecodan Zubadan Puhz Shw Split
The manual says: 63L connector open (low pressure switch connector circuit open).
Part involved: Low pressure switch 63L / connector 63L.
When it shows: 63L connector circuit open for 3 minutes continuously after power-on.
Likely causes:
- 1 Disconnection or contact failure of 63L connector on outdoor controller board; 2 Disconnection or contact failure of 63L; 3 63L working due to refrigerant leakage or defective parts; 4 Defective outdoor controller board.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Not stated as auto-recovering in the service manual; code is logged in the outdoor unit error history.
Manual reset: Clear via RESET on the main remote controller after the cause is fixed; service manual actions include switching power off and on to recheck.
What you can check
- Note the code, unit and ref. address shown on the main remote controller and contact your installer (Mitsubishi user manuals: 'Make a note of the error code number and contact installer'). Check the heat pump breaker/isolator at the consumer unit is on and read the primary system pressure gauge (if fitted) so you can report it. A single reset from the main remote controller (RESET, then Yes) may be tried; if the code returns, do not keep resetting. Do not open the outdoor unit, cylinder/hydrobox or any casing.
What the engineer will check
On the Ecodan Puhz Sw Split
- 1 Check 63L connector; 2 Check 63L side of connecting wire; 3 Check refrigerant pressure, charge additional refrigerant, check 63L continuity, replace low pressure switch if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Puhz W Monobloc
- 1 Check 63L connector; 2 Check 63L side of connecting wire; 3 Check refrigerant pressure, charge additional refrigerant, check 63L continuity, replace low pressure switch if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R290 Puz Wz
- 1 Check 63L connector on outdoor controller board; 2 Check 63L side of connecting wire; 3 Check continuity of 63L with tester, replace if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R32 Puz Wm
- 1 Check 63L connector on outdoor controller board; 2 Check 63L side of connecting wire; 3 Check continuity of 63L with tester, replace if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan R32 Zubadan Puz Hwm
- 1 Check 63L connector on outdoor controller board; 2 Check 63L side of connecting wire; 3 Check continuity of 63L with tester, replace if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Ultra Quiet Puhz W Vaa
- 1 Check 63L connector; 2 Check 63L side of connecting wire; 3 Check refrigerant pressure, charge additional refrigerant, check 63L continuity; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Zubadan Puhz Hw Monobloc
- 1 Check 63L connector; 2 Check 63L side of connecting wire; 3 Check refrigerant pressure, charge additional refrigerant, check 63L continuity, replace low pressure switch if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
On the Ecodan Zubadan Puhz Shw Split
- 1 Check 63L connector; 2 Check 63L side of connecting wire; 3 Check refrigerant pressure, charge additional refrigerant, check 63L continuity, replace low pressure switch if defective; 4 Replace outdoor controller board.
Who to ask for: Mitsubishi Ecodan-trained heat pump engineer (controls / wiring).
What you might notice
What owners and engineers report
1 owner and engineer report mentions this.
- Heat pump will not start on the Ecodan Puhz W Monobloc: 1 report
Sources
- Ecodan PUHZ-SW(75-100-120)(V-Y)HA-BS Service Manual (OCH755) ↗ · OCH755 · page OCH755 p.22 · Reviewed 23 September 2026
- Ecodan PUHZ-W112VHA-BS Service Manual (OCH562D) ↗ · OCH562D · page OCH562D p.17; OCH439N p.53 · Reviewed 23 September 2026
- PUZ-WZ(85-100-120)(V-Y)AA(-BS) Service_Manual (OCH880) ↗ · OCH880 · page OCH880 p.66; OCH816 p.59 (LED display tables) · Reviewed 23 September 2026
- Ecodan PUZ-WM(50-60-85-112)V(H-A)A Service Manual (OCH727A) ↗ · OCH727A · page 50 (LED display table) · Reviewed 23 September 2026
- Ecodan PUZ-HWM140(V-Y)HA Service Manual (OCH748A) ↗ · OCH748A · page 45 (LED display table) · Reviewed 23 September 2026
- PUHZ-W85-112VAA(-BS) Service Manual (OCH681) ↗ · OCH681 · page 14 · Reviewed 23 September 2026
- Ecodan PUHZ-HW140VHA2-BS / PUHZ-HW140YHA2-BS Service Manual (OCH439N) ↗ · OCH439N · page 53 · Reviewed 23 September 2026
- PUHZ-SHW112-140V/YHA Service Manual (OCH526) ↗ · OCH526 · page 24 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026