No filtered water after changing the filters.

Airlock or Flow restrictor flush - No filtered water after changing the filters.
There may be some air pressure build-up within the system.
Remove one of the twist-on pre-filters (preferably the Ft-82) inside the unit and put it back in?
If there is an airlock within the system, this would resolve the issue.
Another possible reason is that a tiny carbon particle might sometimes come loose during rough shipping within the prefilter and get stuck in the flow restrictor once the filter has been installed. Please see the attached picture for the flow restrictor location. Once it's removed, rinse it out under the running water to flush out any carbon that might be stuck inside. If this also doesn’t work, please let us know, and we will help you place an order and expedite the shipping of a replacement flow restrictor.
The connectors are the same quick-connect type as on the post filter. You must remove the red c-clips to remove the flow restrictor. Once the red clip is removed, hold down the white oval towards the elbow piece and pull the tubing out. Flush the flow restrictor in running water and shake it out a bit before re-installing.
The arrow should be facing up when re-installing. Make sure to re-install the red c-clips.