Braemar fault code 42
Fan proving switch fault.
What 42 actually means
Fan proving switch fault. The heater has asked the fan to run and cannot confirm that it did, so it will not proceed to ignition.
What causes it
- Fan motor failed or seized
- Capacitor gone, which stops a motor that otherwise works
- Proving switch or its tube blocked
- Wiring fault to the fan
- Control board output fault
Most likely first. That order is from what we actually find on site, not from the manual.
Safe to check yourself
No tools, no covers off, nothing to do with gas, refrigerant or wiring.
- Listen for whether the fan runs at all when you call for heat
- That is the extent of it. The rest is inside the cabinet
What we check on site
So you know what you’re paying for.
- Fan motor current draw and winding resistance
- Capacitor test
- Proving switch and tube inspection
- Board output verification
Can you keep using it?
Nothing will run. The heater will not ignite without proving the fan, which is correct behaviour, because firing a burner with no air movement is exactly what you do not want.
What the fix usually involves
Often the capacitor, which is a cheap part and a quick job. Where the motor has gone it is a longer visit but still a stocked part.
Is it worth fixing?
That depends almost entirely on how old the unit is. Past about ten years on hot water and gas heating, and twelve on aircon, a significant repair usually costs more per remaining year than a replacement does — and it’s the same point at which the VEU rebate is worth the most, because old inefficient appliances are exactly what the scheme pays to remove. If yours is young and the fault is a component, we’ll fix it and say so.
Repair or replace? The 10-year rule, and what the rebate is worth →