I am trying to find out why my Totaline P374-1000 thermostat is blank. Does anyone know if this is just a faulty thermostat or is there an issue with the air conditioner?

??

Look in the instruction manual for the thermostat.
It could be bad batteries
It could be no low voltage to the thermostat.
It could be damaged wires.

It is hard to tell from here. You will need to track down all of the above for starters.