I just went thru this with my wagon. If you do the above and yours works great...if not follow the below.

Checking the hose in the rear hatch: The hose goes from the rear washer fluid container up over the passenger wheel well, up the rear roof support next to the rear passenger side door, back to the hatch and thru a black tube on the passengerside into the hatch, and to the nozzel in the center of the hatch.

I had to re run new hose because mine was cracked inside the hatch.

Very importantly there is a small grey check valve in the line near the rear wheel well on the back side. Mine was bad. It took me forever to find it.

Check your lines for leaks with a mity vac by this method.

There are two connection. Find the grey check valve and plug it. Remove the trim around the speakers and rear light. On the passender side you will find a black joiner connection above the headliner. You can hook your mity vac and check that tube.

Then check the tube to the nozzel. With the hatch shut, you sitting in the back of the car you will see a hole behind the nozzel. Using a magnetic philps head srew driver you can remove the nozzel screw and remove it. Plug that tube and see if you can hold pressure. If so the line is good. If not you will have to rerun it.

Hope this helps.