Blank Main Display – Trane Commercial HVAC Help Center

I have seen multiple cases of calls pertaining to a blank display.
The main Display (Control Board) is powered from the HUB PCB Board.
It gets 12 VDC at the CN12 connector, Pins 1/2.
The HUB PCB gets its power through the CN 70 Connector AC Power (BLU)
Power off unit and remove CN70 plug from the HUB PCB and check continuity between the two wires if it shows open the one of the high-pressure switches are open.
This will be 250 VAC or line supply voltage (If the unit is 208/230) that's what it should read.
If the unit is 460/3/60 it will get its voltage from the Transformer (Trans power for Samsung Verbiage)
If its 208/230 it will get its voltage from the EMI PCB at connector CN 22 (White).
The High-pressure switches (Switch) are in series with the CN 70 Connector I have seen these fail causing a power to fail the Main display.
When pressurizing with nitrogen for leak testing, don't pressurize over 590 PSI. as instructed in the install manual, I've see getting around the 630 PSI HPS , it will open and result in a blank display.
If the Transformer fails, this will result in Display going blank.
If the EMI PCB #1 loses one or more fuses this will result in a blank Display.

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