Original message
| COALFARMER
 |  "furnace shuts down before blower starts"
, posted Sat 25 Oct 04:38  
oK since no one has posted any help i have worked on this furnace all day and spent 55 dollars on parts that didnt help, but it gave me a new way to look at this problem.. It has nothing to do with the blower but has to do with the amount of time the burner burns. I have timed from when the burner lites to its shut down and found that the whole burn is 1 minute and 45seconds and i dont think that is long enough to bring the chamber up to temp to trip the fan switch to make the blower come on...So what do i look for now flame sensor? bad gas valve? So far i have put a new fan switch and a new fan relay if anyone has any info please let me know.. thanks steve
save a buck and do it yourself
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Replies:
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| yuri
| "Re(1):furnace shuts down before blower starts" , posted Sat 25 Oct 08:46
Bad thermostat. It drops out the burner and the residual heat in the heat ex trips your limit on the 2nd try. Put a volt meter from W to C and see if it drops out. Should have steady 24 volts. I would pull the burner out and check the back of the heat exchanger. If it is the inshot burner/round chamber I had one split wide open about 2 inches above the point where the flame hits the chamber/flame level. Then it is scrap metal and you are safe.
Yuri
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| | BDtech
| "Re(2):furnace shuts down before blower starts" , posted Sat 25 Oct 12:17
the blower should turn on if the burners are lit for 1.45. blower relay could be busted. start it up and stick a temp. probe in the supply duct. check for 120V to the blower, if u get it, board is ok, blower is defective. make sure its not going off on high limit.
by the way, hvac isnt a save buck, do it yourself job. most of the time it'll leave u without heat and or seriously injured.
BDtech out there
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