- Heat pumps
- Air-to-water heat pump
F718
Vaillant F.718 on an aroTHERM plus heat pump: outdoor fan blocked
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On the aroTHERM plus, F.718 means the outdoor unit fan is not confirming that it turns. Look from outside for snow, leaves or objects at the grilles and clear them without opening the unit; if the code stays, call a competent person.
Safety first
Stop and check this first
- The aroTHERM plus contains flammable R290 refrigerant. Vaillant requires no ignition sources such as plug sockets, switches or lamps, and no sprays, in the protective zone around the unit. Do not open the casing or push tools between the blades.
Safe checks you can perform
- Exact code on the display
- Air inlet and outlet grilles
- Fan motor test
Leave these tasks to a qualified professional
- Do not attempt this professional task: Test the fan before replacing parts
- Do not attempt this professional task: Operating test after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Test the fan before replacing parts
What they doThe technician checks the air path, the motor, the connector and the rpm signal using the unit's actuator test.
They must show youthe fan rpm reading in the test and the state of the connector.
In writingwhat was measured, which part was replaced and why.
Operating test after the repair
What they doAfter the work, the technician starts the heat pump and checks that the fan turns and F.718 does not return.
They must show youthe fan running and the display with no code.
In writingthe date, the result and the R290 leak check done before opening.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Exact code on the display
- Who:
- you.
- How:
- read the message on the heat pump interface display and note whether it shows F.718, F.785 or status S.252.
- Result that matters:
- F.718 is fan 1; F.785 is fan 2; S.252 means it is still in the automatic restarts.
- If you see S.252 and not F.718:
- the unit is still retrying every 15 minutes; wait and watch whether it reaches lockout.
- If you see F.718:
- it has already failed four times; the lockout is firm and the air path needs checking.
- Evidence to keep:
- a photo of the display with date and time and the rough outdoor temperature.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
Air inlet and outlet grilles
- Who:
- you, from outside and without opening the casing.
- How:
- look at the air inlet and outlet grilles of the outdoor unit and remove snow, leaves or branches gathered around it, as Vaillant lists in the user care section.
- Result that matters:
- that the air path is clear and no ice is holding the blades.
- If there was snow or leaves and the code does not return after clearing them:
- the obstruction was the likely cause; note it.
- If the air path was clear or the code returns:
- a visible obstruction is ruled out; call a competent person.
- Evidence to keep:
- photos of the grilles before and after clearing.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
Fan motor test
- Who:
- a Vaillant competent person.
- How:
- with the unit isolated and checked leak free with an R290 gas sniffer, they inspect the fan motor, its connector and the speed signal, and run the fan from the test menu.
- Result that matters:
- whether the fan turns and the board receives the rpm signal.
- If the fan does not turn with a clear air path:
- a fault in the motor or its supply is confirmed.
- If it turns but the board sees no rpm:
- the signal wiring or the board is the suspect, not the motor.
- Evidence to keep:
- a job sheet with what was measured and the part involved.
Opening the outdoor unit requires isolating all poles, waiting at least 3 minutes for the capacitors to discharge and checking with a gas sniffer that there is no R290 leak. Competent person only.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- Vaillant
- Product type
- Air-to-water heat pump
Known code variants
- aroTHERM F.718
- aroTHERM plus F718
- Genia Air F.718
- Genia Air Max F718
- Saunier Duval F718
- Vaillant F718
What it means
Vaillant links F.718 to fan unit 1: the board gets no signal that the fan is turning. Status S.252 acts first: with the fan at 0 rpm the heat pump stops for 15 minutes and restarts; after four failed restarts it locks out with F.718. The code does not tell an air path obstruction from the fan motor, its wiring or the board: a technician separates those. F.785 is the same fault on fan 2.
Warnings and stop conditions
- Highsource verified
The aroTHERM plus contains flammable R290 refrigerant. Vaillant requires no ignition sources such as plug sockets, switches or lamps, and no sprays, in the protective zone around the unit. Do not open the casing or push tools between the blades.
Evidence: Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
Symptoms and causes
Probable causes · in order
- Blocked air pathCommon
Snow, ice, leaves or objects stop the blades or cover the grilles. It is the only cause Vaillant's table asks you to check and it is usually visible from outside.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
- Fan motor or its signalPossible
If the air path is clear and the code returns after the four restarts, the speed signal is missing because of the motor, the cable or the connector. Only measurement with the unit open separates them.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
- Strong wind before startLess common
Vaillant has a separate status, S.287, when the fan already turns at 50 rpm or more before starting because of outside wind. If you see that status and not F.718, the cause is different.
Evidence: Vaillant VWZ AI heat pump appliance interface, operating and installation instructions 0020291573_01 · Vaillant aroTHERM plus VWL 35/6 to 75/6 A S2, operating, installation and maintenance instructions 0020330791_03
Virtual technician
Does F718 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
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