This is going to sound really weird, but I had precisely that in my machine for a couple of years, but only occasionally. To make it worse, there was a local disabled woman I used to give lifts to, to the shops etc, and I was always really embarrassed, telling her that honestly, I REALLY hadn’t NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-, it was the aircon etc etc etc.
She was always very good-humoured about this. The odd thing was though, since she moved house a couple of years ago and I've stopped giving her lifts, it’s never happened again… sometimes I have to be hit between the eyes with a brick to see the bleedin obvious