View Full Version : Ac Jr. question

09/18/2005, 11:11 PM
Channel 6 on my AC jr is setup to run my fans and it works fine. The problem is on the display channel 6 shows up as U. (undefined)
I deleted the name and made a new name, same name of course, and it still didn't clear that. I changed the symbol in the name and that didn't work either. It was showing up fine and then all of the sudden it went to U.
Any ideas what's going on?

09/19/2005, 07:08 AM
The controller turns the device to "U" when you change the program and it has not met the evaluation criteria. For example, when I make changes to my heater program, it will register as "U" until the temp is below the desired temp and then the AC will trigger it / turn it on and will no longer be "U" or undefined.

09/19/2005, 09:45 AM
Sometimes you can fix this using:


Use this statement as one of the first in your programming followed by the regular code for fan off and on statements depending on your conditions. This will put the fan in a defined mode at the onset.

09/19/2005, 11:37 AM
thanks, I got up this morning and it was fine but now I have another problem. My closed loop pump was off.
I used the command IF TIME > 00:00 THEN PM1 ON
I have no idea why it would have turned off. I went in to modify state and was messing with the code and it came on. I put the code back exactly as it was before and it's running right now. I hope it stays on.

09/20/2005, 01:22 AM
I could be an order of operations issue. I think the best way to initilize your pumps and such would be at the very top of the program list.

09/20/2005, 01:40 PM
The 'U' means undefined, and can be a normal status display for a period of time. It basically indicates since power-up or program modification change, no program statement for a particular timer name has ever been true. For example if you had temperature statements like this:

If Temp > 80.0 Then COL ON
If Temp < 79.0 Then COL OFF

and the temperature was 79.5 and the controller was power cycled, the COL timer would be undefined until the temperature either rose above 80 or went below 79.0.
You don't need to or want to add the default ON statement for this case either. If you do you'll loose the dead-band between the high and low temperature set points, and the chiller/fan may cycle on/off frequently.