Noob RO/DI question


Reefing newb
My wife and I have an RO/DI system that serves a few aquariums in the home and I just installed an evap air unit to take some of the A/C load off of our electric bill. My question is, is there any reason why I cant "t"-off of the RO line going into the reserve tank before the tank and take a second line over the evap air cooler? I understand that the holding tank automatically shuts off the water supply when it's full, I assume using pressure as the trigger and that, when water is removed from that tank for aquarium use, the drop in pressure triggers the unit to make up more water and then shut down again. The evap cooler uses a conventional float inside to control water demand so in my thinking, if the reserve tank is full and the evap air cooler demands water via the float mechanism, that should trigger the RO unit to make more water and when the cooler is full and the floats stops the water demand, the unit should just shut down until either the reserve tank or the evap cooler demands water. But, our wast water is running constantly even when there's no physical demand from either the reef tank or the evap cooler. Any thoughts?
Sounds like the restrictor is open for some reason. That means you get to take it apart and see if that's what's wrong with it, uggh.
There's a small plastic piece on the waste water side of the RO unit, most look like a plastic coupling. If it gets debris in there it stays open and it will run all the time. Mine was stuck closed and the RO wouldn't run at all.