PUHYP400MFB Indoor Units Stay in Cooling

[woody100]

Hello,
I'm working on a Mitubishi PUHYP400MF-B which is connected to a Procon Y-ACO. From what I can gather the Y-ACO has a room sensor and dictates whether the outdoor unit runs in heating or cooling. My problem is that even when I raise the temperature on the Y-ACO and the green light goes off (indicating heating) the indoor units remote will not go into heating, they stay in the cooling mode even if the remote setpoint is raised. I would appreciate ny help with the above.

[JoeAT50A]

Indoor unit SW 3-1 may set to ON (Cooling only instead of Heatpump). (Unlikely but check)

Check on Outdoor's Auto change over CN3N (3wire adaptor cable)

1 and 2 short/closed >> heating only
1 and 3 short/closed >> cooling only

Most likely Procon interlock with this.

Hope this will help.

[woody100]

Thanks JoeAT50A,
i'm due back next week so i shall have a look then

[stufus]

Check the dead band setting on the YACO.
Mode shift is set point +/- dead band depending on original mode to avoid space temperature swings.
Is the controller in Automatic mode??
Cheers
Stu