gas furnace problemsgreenspun.com : LUSENET : Freedom! self reliance : One Thread
My furnace is at least 30 years old. I have replaced two fan/limit switches, 1 blower motor and 2 belts. No matter what, my blower is constantly running. The burners cycle on and off ok, but the blower continues to run. I have moved the pin settings on the fan/limit switch to every possible position, but the blower stays on. Does anyone know if this is normal for some furnaces, or what could possibly be wrong.
-- Cheryl (firstname.lastname@example.org), January 24, 2004
Cheryl! No it's not normal. I assume your's is a "rotary" dial switch with pointers to set the temps. The fan off should be around 90f--fan on---about 120f and limit about 165-180f. I don't know what kind of furnace etc you have nor do I know the type fan/limit switch it is but most older ones had the Honeywell or White Rogers with a "probe" that ran inside the furnace. They had an insertion length which was longer back in the good old days. I wonder if the replacements were the same length as the old ones.
IF it's the same length as the old orginal then there is only two things that can cause it to run. A faulty fan switch [new ones are sometimes bad outta the box], fan on temp is set too low. Another thing is possible--the fan is wired up thru the limit switch rather than the fan switch.
With al little more info I mite be able to help more. Also--does it have central A/C? old hoot. Matt. 24:44
-- oldhootgibson (email@example.com), January 24, 2004.
faulty relay switch, witch is attached to the circuit board on older models.
-- Eric blankenship (Eblankenship5@aol.com), February 23, 2004.