Can your ammo rack explode if it has no ammo?

Solution 1:

No, your ammo rack will not explode when it reaches 0 hitpoints if it has no shells left. The number of shells in the ammo rack above 0 does not influence the chance of it exploding. If at least one shell is in the ammo rack and it's hitpoints drop below it will always detonate.

If the ammunition rack's hitpoints reach zero, it explodes, destroying the tank and its crew completely regardless of the remaining hitpoints on either of them. The only case the tank does not explode with a "red" ammo rack, is when the rack is completely empty.You can increase your ammo rack's hitpoints by installing "Wet" Ammo Rack equipment or by training the Safe Stowage perk on a crew member with the role of loader.

Source: wargaming wiki