Suburban Furnace Problem

[Riverc]

My furnace in not working right.It will work 2 or 3 times fine.Then it comes on sail switch clicks blows hot air during that cycle I hear the sail switch click 2 times the furnace shuts down and will not come back on at preset temp.I have to shut on off switch at thermostat for it to work again.

[MnTom]

Time to do a bit of troubleshooting. It kind of sounds like it is locking out and using the switch on the t'stat resets the board. Generally the only reason they lock out is from loss of flame. If it was the high limit the furnace would come on again. There should be a flame rod that sticks into the flame that proves the flame to the safety system. If you can, pull the burner and clean the flame rod. It may not look dirty, but either use a Scotchbrite pad or some steel wool to polish it up.

[mel s]

Originally Posted by Riverc

My furnace in not working right.It will work 2 or 3 times fine.Then it comes on sail switch clicks blows hot air during that cycle I hear the sail switch click 2 times the furnace shuts down and will not come back on at preset temp.I have to shut on off switch at thermostat for it to work again.

Riverc
See the trouble shooting instructions in this pdf: http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

BTW I very much doubt that the click you hear is the sail switch.
When the sail switch in my Suberban in my SF-42F furnace closes or opens it doesn't "click" loud enough for me to hear...(however I can hear the click of the "gas valve").

Mel
'96 Safari

[Old-Biscuit]

Originally Posted by mel s

Riverc
See the trouble shooting instructions in this pdf: http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

BTW I very much doubt that the click you hear is the sail switch.
When the sail switch in my Suberban in my SF-42F furnace closes or opens it doesn't "click" loud enough for me to hear...(however I can hear the click of the "gas valve").

Mel
'96 Safari

Exactly^^^^^^^^^

Hot air blowing means main flame is lighting off........but then dropping out and locking out due to 'lack of flame proving' That is why you have to reset using the t-stat
Flame proving is done by 'flame ionization' ---a milivolt signal is generated and sent back to circuit board -----no signal board shuts down gas valve. Usually will make 3 attempts then lock out

Burner slots obstructed and flame isn't engulfing spark electrode
Spark electrode is not centered over burner slots
Spark gap is not correct---S/B 1/8"
High Tension wire from board to electrode connections are loose/dirty (doesn't take much resistance to stop milivolt)
Ceramic is cracked allowing milivolt signal to jump to ground

Which Suburban Model do you have??

[Riverc]

Well not 100% sure yet my battery checked out good.I turned both tanks off lit burner on stove till all gas was out of lines it's seems to be working for now.If if acts up again will have a tech look at it Thanks for the help guys.

[Riverc]

Well took Furnace to shop for a bench test.Got the call tech said everything was good.
Put it back in it did the same thing.Pulled it again checked the flame sensor it looked bad thought that had to be the problem put a new one in,wrong.
Pulled it again changed the Gas Valve it's running good,hope that's the fix.