I recently installed a Ruud furnace model #RGPR-12EARMR 125M (2STAGE W/ICM 80%) It replaced a long running 5 ton furnace in the same system. I haven't tested the gas burning parts yet, just using the blower for A/C. The installation manual is here:
It has been operating for a week or so without problems. When the power is on, there are two greed LEDs lit on the control board. When the blower is running, a red LED (labeled CFM on the circuit board trace) is mainly on and winks off about once a second. I cannot find any documentation about the red light, and Ruud/Rheem tech support gets huffy when I call to ask.
Another HVAC tech mentioned that a red light is normal on some units and a sign of problems on other units, so you just have to look it up to know the answer. Does anyone know the meaning of the red CFM LED on this Ruud furnace?