HVAC fault codes,
sourced from manufacturer manuals.
Look up a fault code on Mitsubishi Ecodan, Daikin Altherma, Toshiba or Gree — get the official procedure with the source in seconds. Built for F-Gas registered engineers across the UK and Ireland.
Mitsubishi Ecodan, Daikin Altherma, Toshiba, Gree — UK & Ireland coverage
Ask Marcel is an independent tool. F-Gas work must be carried out by a registered engineer. All brands belong to their respective owners.
Knowledge base
Popular fault code guides
E3DaikinFault Code E3 Daikin Altherma 4: Causes, Diagnosis and Solution
Daikin E3 fault? Protection triggered, inconsistent measurement, or abnormal event. Correction depends on confirmed cause: wiring/sensor, or operating condition.
7HDaikinFault code 7H Daikin Altherma 3: quick diagnosis
Fault code 7H Daikin? In many cases, restoring correct flow (bleeding, filter) or fixing a poorly fitted sensor is enough. To avoid an approximate diagnosis.
A3DaikinFault code A3 Daikin Altherma 3: causes and solution
Fault code A3 on Daikin Altherma 3? Often fixed by restoring circulation, bleeding air, and cleaning filters. If the code persists, follow specific Daikin checks.
F3DaikinFault Code F3 Daikin Altherma 4: Diagnosis (Sensor / Protection)
Daikin F3 error? An F3 is often resolved by restoring a sensor/connection or by correcting the condition that triggers the protection.
01AtlanticFault Code 01 Atlantic Air Conditioning: Communication Problem (Serial Link)
Fault code 01 on Atlantic air conditioning: silent unit, unstable flaps? Serial link cut between indoor and outdoor units. Check 3-core pilot wire, power supply and PCB: field guide.
L5Mitsubishi ElectricFault code L5 Mitsubishi Ecodan: Water flow fault
Mitsubishi Ecodan fault code L5? Dirty strainer filter, closed valves, air in circuit. Restore nominal water flow. If filter is clean and pump runs, check temperature sensors.
The breakdown isn’t
the problem.
The real cost? The minutes wasted searching for the right info while the customer waits and your schedule falls apart.
Time lost per breakdown
+30min
Hotline + doc search + hesitation
Hotline overloaded
Endless waiting while the customer watches.
Missing PDFs
12 folders, 47 manuals — and the right page stays hidden.
Return visit
Wrong diagnosis = second trip, margin goes up in smoke.
"The customer is watching. The hotline puts me on hold. I lose credibility in real time."
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AI Vision: stop typing, start scanning.
Take a photo of the nameplate, the error code, or even the flame on a stove. Marcel identifies the model and context instantly.
TARGET DETECTED
MITSUBISHI ECODAN PUHZ-W85VAA
The brain: sourced, not guessed.
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Database search
50,000+ HVAC issues indexed
VERIFIED SOURCE:
Atlantic Alféa Extensa A.I. installer manual
— Page 34, Section 5.2
Action: leave with the fix.
Step-by-step test procedure, resistance values, and the official part reference. Close the ticket on the first visit.
REPAIR VALIDATED
Measure the flow sensor (terminal block X5, 1-2)
Expected value: 12.5 kΩ at 20°C
Official service part
NTC 10K SENSOR — REF: 567843
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"At first I was skeptical about AI. But when it gave me the right sensor value for an old Atlantic heat pump in 10 seconds, I got it. It’s my expert apprentice."
Julien
Plumbing & heating contractor (69)
"I do a lot of pellet stove maintenance. Having service codes for all brands in my pocket saves a ton of time."
Marc
Service technician (33)
"Finally a tool that understands technical jargon. No more scrolling 200-page PDFs on a roof."
Thomas
Refrigeration tech (13)
"Doing flue sizing calculations live at the customer’s site is the argument that closes the sale."
Antoine
Wood/biomass installer (44)
"Marcel helped me diagnose an intermittent fault on a complex gas boiler. Huge peace of mind."
Sébastien
Heating expert (75)
"The UI is super simple, even with gloves or on a noisy site. Adopted by my whole team."
Nicolas
SME owner, HVAC (31)
"At first I was skeptical about AI. But when it gave me the right sensor value for an old Atlantic heat pump in 10 seconds, I got it. It’s my expert apprentice."
Julien
Plumbing & heating contractor (69)
"I do a lot of pellet stove maintenance. Having service codes for all brands in my pocket saves a ton of time."
Marc
Service technician (33)
"Finally a tool that understands technical jargon. No more scrolling 200-page PDFs on a roof."
Thomas
Refrigeration tech (13)
"Doing flue sizing calculations live at the customer’s site is the argument that closes the sale."
Antoine
Wood/biomass installer (44)
"Marcel helped me diagnose an intermittent fault on a complex gas boiler. Huge peace of mind."
Sébastien
Heating expert (75)
"The UI is super simple, even with gloves or on a noisy site. Adopted by my whole team."
Nicolas
SME owner, HVAC (31)
"At first I was skeptical about AI. But when it gave me the right sensor value for an old Atlantic heat pump in 10 seconds, I got it. It’s my expert apprentice."
Julien
Plumbing & heating contractor (69)
"I do a lot of pellet stove maintenance. Having service codes for all brands in my pocket saves a ton of time."
Marc
Service technician (33)
"Finally a tool that understands technical jargon. No more scrolling 200-page PDFs on a roof."
Thomas
Refrigeration tech (13)
"Doing flue sizing calculations live at the customer’s site is the argument that closes the sale."
Antoine
Wood/biomass installer (44)
"Marcel helped me diagnose an intermittent fault on a complex gas boiler. Huge peace of mind."
Sébastien
Heating expert (75)
"The UI is super simple, even with gloves or on a noisy site. Adopted by my whole team."
Nicolas
SME owner, HVAC (31)
"At first I was skeptical about AI. But when it gave me the right sensor value for an old Atlantic heat pump in 10 seconds, I got it. It’s my expert apprentice."
Julien
Plumbing & heating contractor (69)
"I do a lot of pellet stove maintenance. Having service codes for all brands in my pocket saves a ton of time."
Marc
Service technician (33)
"Finally a tool that understands technical jargon. No more scrolling 200-page PDFs on a roof."
Thomas
Refrigeration tech (13)
"Doing flue sizing calculations live at the customer’s site is the argument that closes the sale."
Antoine
Wood/biomass installer (44)
"Marcel helped me diagnose an intermittent fault on a complex gas boiler. Huge peace of mind."
Sébastien
Heating expert (75)
"The UI is super simple, even with gloves or on a noisy site. Adopted by my whole team."
Nicolas
SME owner, HVAC (31)
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