1994 Nissan Maxima: fuel smell from heater

I have a problem with 1994 maxima. A strong fuel smell comes in the
coupe through the heating system for a few minutes after the heat goes
on, and then it disappears. This happens on cold days only (-10 to -15
degC, 14 to 5 degF) and I cannot smell fuel in the engine compartment.
I have a model with automatic temperature controlled heat.
I had Nissan Dealer look at this 2 year ago and they replace one of the
fuel hoses, which was cracked. The problem went away for that winter
and the following, but has come back again. I have inspected most
hoses in the engine compartment except the ones that you need to get to
from below. I'd like to deal with this one myself, since my garage
inspected the fuel system and saw nothing wrong, or they said they did.

Q. is it possible for the problem to be caused by something else than a
faulty hose? If so what is it?

Thank you