The potential fixes for this are very simple if you take it step by step. The first step is to verify the standing pressure. Use a set of gauges tied in the service ports next to the transducer. Once the gauges are installed use the Comfort Link to verify the pressures of the Gauges. If they are off more than 10 psi the bad transducer needs to be changed. If the transducer’s reading is good verify the control voltage to the contactors and make sure there is no loss going to the contactors from the MBB. Make sure you have the signal out of the scroll protection module. If those are present and the transducer is fixed the problem is solved.