I am asking this question for a friend's ac unit. He gots a Rheem 4 ton with a rbhc-21j11sfc air handler. Its a 2005 model I saw on the label. I don't know which condenser he has but the question pertains to the air handler. I came over his home to help change his tstat because the old one seemed to not work when you turned on the heat mode. It would just say heat but the air handler didn't turn on. No blower sound or anything. So we changed the tstat and everything is fine.
But on the wiring diagram on the air handlers cover, I read in the notes part it says "For single stage heat connect White/BK and White/Bl with "W" connection on SB" (SB must be the tstat) .
His unit is a single speed air handler and also he does not have a heat pump just basic electric strip heat.
Now the White/black wire inside the air handler is not joined together with the White/Blue wire. I saw where the wire leads to and based on the diagram it says it comes off the HR1 which is the Heater relay 1.
The White/Blue is wired to the HR2 or Heater Relay 2. The White/Blue wire is connected to the W terminal on the tstat. So should we do what it says? I can just connect the white/blue and white/black together inside air handler, which then connects to the tstat W terminal. I am wondering if that heater relay is not connected does it mean maybe one of the coils are not connected or turning on and off? The heater does turn on and it seems like some sort of heated air is coming out of the vents but I think it could be better and stronger. I also believe his blower maybe set on too high. I think his unit has factory installed 7.3/9.8 kw , that's what it said on the label of the air handler.
And one more question if we want to lower his blower speed...where can we do that on the air handler? I don't see any dip switches or anything indicating how to change it. It seems to me its maybe somewhere on the blower it self?