AHU not responding correctly to the TAC BMS panel.

[Aqeelhassan]

I've 3 Carrier AHU's who are not responding correctly to the TAC BMS control system.
if the unit is turned off by time programming with the TAC panel it gets off but the status still shows running and the actuator does not shutoff.
i've checked and cleaned the sensors but it did not work, please advise how to rectify.

[Brian_UK]

Is the TAC system working correctly?

[Emmett]

What does TAC stand for? Tour Andover Controls? If it is then the status you refer to is likely called a numeric point and would be on or off based on a program and although the unit is not running the "virtual Point" thinks it is running and that virtual point is likely controlling your actuator.

[goshen]

hi check communication cable to the tac controller from panel.
make sure u didnt exceed the recomended distance.
What xenta model controller are u using?

[Tesla]

Check your air press switch on ahu, this is where the status (run) should come from.

[Aqeelhassan]

Yes, i've 13 AHU's and all response properly except 3.

[Aqeelhassan]

I've checked and cleaned the air flow sensor.
I use TAC Xenta OP.

[goshen]

Could be a software problem-maybe the input wasnt programed properly?

[The captain]

Whats the front end telling you about the FCU's status?

[goshen]

hi aqeelhassan
whats up??did u find the bug??

[Tesla]

This point (run status) could be in the manual forced on from a software override. But from experience there is usually another fault or two. Do you have acess to manually override points on the front end or laptop? You can trace the cable from the air press switch with a bell or fset to the controller board input or mech pannel to determine if it is a software or hardware fault. I found on a big site with TAC and York AHU's that innitial commissioning was not completed - causing the CHWV to stay open when fan is not running inturn causing chiller short cycling and a very mouldy coil.

[Aqeelhassan]

no goshen, not yet...any idea?