I have traced the rotten egg smell I was having intermittently. It is from
the front windscreen washer fluid. It now clicks into place that the only
time I got the smell was when I used the washers. Then the fluid would have
run down the front of the grill into the air intake. This is why it seemed
to come from the hot air system but only when the vehicle was moving, not
by the blower.

I presume some bacteria in the washer bottle are producing hydrogen
sulphide. Any suggestions on how to flush out the creatures? Eg is it
simple to take out the bottle, or can I drain it OK by squirting the
windscreen? If I poured bleach in the bottle will it harm the rubber pipes?

Lionel Tun
1984 Caravelle GL, 183k miles
lionel@ark.prestel.co.uk