Re: hotpoint wd420
I take it this is happening without you having selected the tumble dry function.
If you are absolutetly certain that the dryer knob is in the OFF position then the fault could be in the control module or the main power module.
As one is around £70.00 + vat and the other even more expensive you would be well advised to contact Hotpoint/Indesit. your machine has a 5 year parts warranty so you would only have to pay their modest, 🙄 😥 £90.00 labour charge.
Not a fault I have come across, if you don’t fancy Hotpoint then click the link in my sig to see if we have someone who can help.