I'm trying to install a wireless thermostat but i ran into issue putting in an external thermostat. I have a 2 Stage Cool / 1 Stage heat system.
I have the Red 24V from Air Handler connected to R. I have a external 24 Volt Transformer Hooked up to Rc, and C. I get 27 volts between Rc, and C. However when i tell thermostat to turn on fan nothing happens. If i remove external transformer and jump Rc, and R using AHU transformer everything works fine.
What could be causing this?