I have 2 Waterfurnace Envision Series NSZ030 geo units on a closed loop system. One of the systems has been trowing a "Water Flow" error (atleast thats the light that comes on) every so often. When I open the front panel the yellow light is blinking 3 times which indicates a "Short Cycle" problem. Here is where things get kinda tricky: This happened 3 times in the first year of ownership. The installer ran into a few issues with water pressure (the well pipes expand) and such. After the first year this has not happened again until now (5 years later). The issue came up just before my yearly maintenance check so the tech was here to see the problem. At first he thought the coils or condenser were bad but went through alot of checks and at one point switched over to AC mode and then back (we did the 5 min wait time between unit switching). The condenser appeared to work ok so his next thought was the freon (or whatever its called today ) - thinking that might be low he connected his tank but only a few ounces were required. After his complete check the unit was working great once again. Fast forward 1 month and the light came on (I know when this happens since my upstairs gets cold since something is not working to generate heat). There is a plug inside the unit which can reset the lights and during my first year of problems was told to try this to see if things get rest. Well I did this and the light would come back on. The compressor is definitely running as its making a sound. Whats not happening is the copper coil is not getting warm (the refrigerant is not getting charged?) - Im also not sure if the water is flowing since the EWT and LWT were the same temperature. The other unit is connected to the same well piping so when that kicked in I can read a difference in water temp. So Im sitting here scratching my head - the green light turned off so the system was not functioning well at any level........................... After sleeping on this I remembered that we turned the AC on during the maint check so this morning I used the termostat to shut the unit down - waited 5 mins - switched to AC and turned the temp down. If of course felt cold , but in checking the Geo Unit the EWT and LWT were showing a difference and the copper coil pipe was really cold. After letting it run 10 mins I turned it off via the thermostat, waited 5 mins and switched back to heat. Wala, the heat is running like normal..........the Water Flow light is still on but Ive read that the system needs to havee x amount of successful cycles before turning that off................ So any thoughts on why I would get a short cycle error on Heat mode that is corrected by switching to AC mode and back????