sounds electrical, you will need a volt meter.
1 is there 24vac to the contactors(is the transformer powered?)
2 is 1 or both or the overloads on the contactors tripped
3 is the plc for the dryer powered?
4 is both the main breakers on? (panel in equipment room)
the nozzles share a power supply with one of the blower motors,so the nozzles can run without the dryer blowers being on. I would check the 24n wires first,and make sure the overloads are not tripped.
You may already know this,but there are 2 power supplys to the dryer,and the wires land on the top side of the contactors.so be sure to check that both supplys are on,use a volt meter to verify.
should be fairly easy to track down,but you will need a volt meter to test all the systems.