E74 error thermostat

[Noodlemantra]

Hi,

I just switched over to a nest thermostat and the system has the error that there’s no power. I’ve triple checked the wires, checked the drip tube, and checked the fuse. Where do I go from here?

[Patrick_Caezza]

@Noodlemantra 

The quickest way to verify if there is 24vac on the R wire is using a volt meter, if you don't have one you can connect the R and G wires together and the blower should turn on. If it doesn't then there is a cabling problem of the fuse in the furnace/air handler might be blown.