I built my house in 2004 builder installed a Bryant 90+ 350mav048100fgka. From what I remember, when you selected fan to ON it was a lower blower speed. My wiring diagram identifies BFANR with a red wire plugged in which is the same on the circuit board. I can not find any info even calling Bryant as to if a relay has gone bad or bad wiring. I can not figure out why I cant get a low blower speed back a wire is plugged in. My information manual is incorrect too because the label on the furnace door calls out "continuous fan select relay, SPDT". Sometime between 2004 and now I lost this feature of a lower speed when I could run the blower through out the day or night and when it called for heat or cool the blower would ramp. I'm going to go back and install the round Honeywell stat that was in the house when built to see if the feature was disabled when I installed a programmable stat. Actually I thought maybe I was wrong on this feature, but the furnace schematics list the feature in Notes but can't find any supporting info.
Being new to the forum I'm going to suspend this question until I can do more testing. Being a mechanic and engineer something isn't right. Thanks for the comments