On a older Armstrong furnace, Its a Ultra II model EG6E, (circa 1990)
Were these systems designed/wired so as to have the blower come on right away with the t-Stat "call for heat"?, instead of relying on the limit control temp's on setting to power up the blower?
Looking at the schematic and studying it, and studying the relay's, it appears that the NC side of the fan relay (not energized in heat mode,energized with A/C only ) is getting power via the energized NO, STDP combustion relay, and cant help but power up the blower low speed with the initial start up of the furnace.
The limit control has been replaced.
Manual/Auto on limit control is set to auto.
Fan on/Auto on T-Stat is set to Auto.
Sorry I don't have a scanner to scan/E-mail the schematic.
I will try to get it scaned so I can post it.
Thank You, Anthony Diodati