2000 v70 turbo coolant problem

here's a puzzler - the overflow tank keeps emptying but the car has never
run hot. it has no signs of a head gasket problem afaik (anyone want to give
me other warning signs besides coolant in oil/oil in coolant/white gunk on
oil cap/etc) i'm actually hoping maybe on of the hoses that goes to the
overflow tank itself is leaking but there is never any coolant on the ground
just condensation from the A/C pipes. ps- i looked around the timing belt
for signs of a water pump seal going bad but there is never any steam or
water leaking from there either.
thanks in advance for any help everyone!

 

Check the coolant reservoir these usually leak also check the bottom of
the radiator for any signs of leakage

 

I'll second that. Mine was cracked but would only leak when under
pressure in operation. When you check it, unless it is hot and running,
you won't see a leak.