Not sure what you mean by this. Are you cooling the air that you’re then feeding into the GF? Otherwise not sure how you get cooler air than ambient with the passive cooling of the GF (yeah, it’s fan assisted, but it’s just going through a radiant heat exchanger and that heat exchanger is dumping hot air into ambient so it doesn’t seem that the coolant could be cooler than ambient). The peltier cooling of the Pro should be able to drop below ambient because it consumes power to create a cooling differential.
Mine hasn’t worked about 78F. I’ll have to check it tonight when I get home. Working on my chiller tray anyway. I have an infrared temperature wand I use to point & shoot temps so I’ll see what the heat exchanger says.