York YCAS1215 Current/HP/MPX

Hello,

I have been working on a York YCAS1215 chiller which has 4 screw compressors. I am getting a Current/HP/MPX fault on 1 of the circuits.
I have checked for this fault before and have found various reasons (HP cutout, Motor Protection) and I am used to the basic circuit from the relay board through the HP, MP and then to the Texas Instrument controller. My problem this time is that when the display says the compressor is running, the contactors do not pull in. The power for the contactors starts at the relay board from terminal 20 and then goes to the HP, Mp etc. However, when the unit tries to start, you can hear the relay on the board click but there's no power from terminal 20 so the unit will not start and after 3 attempts it trips on Current/HP/MPX. Any Ideas?

Your texas instrument module is faulty

I'm going back next week so i'll try your suggestions then - Thanks