Arzel panels have built-in diagnostics that prevent certain thermostat calls from being served. When that happens, you might see a "-ILL" on your screen. Learn how to understand these exceptions so you can shorten your diagnostic time.
An illegal call is where we get an input from your thermostat that shouldn’t be recognized by the Arzel panel. Rather than damage your equipment by allowing that call to go through, we’re just going to ignore it. And you can see an illegal call with the HeatPumPro by going to your zone screen. Zones 1, 2, 3, and 4. Once you go to those screens, on the call line you’re going to see “-ILL” next to whatever inputs are receiving from your thermostat.
So we know that we have a call from our thermostat but absolutely nothing is happening at our Arzel panel. So first off, we can go to our zone 1 messages. We have a call for heating and we used a heat pump thermostat, but it says it’s illegal. We have W1Y1GO – ILL. If you see that message it’s because your reversing valve is energized in heating. If you use a heat pump thermostat on zone 1, reversing valve is only energized in cooling. You can clear that fault code quickly by disconnecting your O wire. That will allow the heating call to go through. So now we’ve disconnected our O wire. We have W1Y1G – heating. Something you might also see: if you use a heat pump thermostat on zones 2, 3, or 4, they only accept heat/cool thermostats. But if you were to use a heat pump thermostat, you might actually energize both heating and cooling circuits at the same time. You could see a WYG – ILL. This could also be if your thermostat wire is pinched or if you have a faulty thermostat. Now if you want to call for heating, you would disconnect your Y wire and that would allow the heating call to go through. If you want to call for cooling, you would disconnect your W wire and that would allow the call for cooling to go through. So right now we’ll let it go for a cooling call. We’ll disconnect our W wire. That clears the illegal call and now we have YG – CLG. In zone 3, we have Y – ILL. If you have a call for cooling, you have to have a call for both Y and G at the same time. If you’re missing that G, the HeatPumPro is going to view that as an illegal call. And the fastest way to test that out is to place a jumper across your Y and your G. And of course I hit the button.
So now that we have Y and G jumpered out we have YG – CLG. The board allows that cooling call to go through. We know the HeatPumPro is working correctly.
