> "f) Furnace continues to fire....at about the 50 second point (from
> when I powered the furnace ON) I hear a relay click (at t+50s)"
> I have a feeling this click is the fan relay. See if you can find it on the
> control board. It is possible the 120 volt leads to the relay on the
> printed circuit board may be loose... bad solder joint. But your test does
> indicate the blower relay is the cause. Since you hear the click it seems
> the coil is being energized. So either the 120 volts on the line side of
> the relay (power in) is not there or the relay contacts are bad and there's
> not 120 volts on the load side (power out to blower).
> Do not use dashes, slashes or question marks. Due to spammers these
> punctuation marks will cause an * do be displayed.
thank you for your insight. I am somewhat in agreement, but, what prevents me from being 100% sure it is related to the BCC, is the fact that I can run the blower by jumping the R and G terminals. I am assuming that there is only one blower relay. The 24vdc control voltage could come from two differnt logic sources (e.g. manual blower on/off, and local bcc blower control on/off). The 'line side' (120vac through the relay contacts) feed to the relay contacts to the blower motor would only come from one source (and only one circuit path on the bcc).
The Figure from the lennon manual shows that the time delay relay, K36, feeds the blower red (heat) wire via contact K36_1, and the relay K3 feeds the blower black (cool) wire via contact K3_1. Soooo there _are_ two separate relays and K3 is infact controlled by the Blower Manual On (connected to G) at the thermostat. So now I am more conviced that the K36 relay contacts are not working properly. I've worked with relays for over 30 yrs and on only one occasion have ever seen relay contact fail....switching and inductive DC load that was not properly snubbed, so I find it weird that in switching an AC load, the contacts would get carboned up....I doubt dirt b/c I assume they are sealed - or should be....and the contacts should be properly sized so there is not detoriation due to excessive current, although the designer may have not considered 6xto10x FLA in rush at startup....
So, how can I upload a picture here (question mark)
Wish I had the schematic of the bcc. Know where I can get one (question mark)
A quick Google search seems to indicate that, there is one replacement board: bcc3 which is backwards compatible with bcc2 and bcc1 and variations. Can you confirm (question mark)