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-   -   Furnace starts then shuts off and tries again (http://www.diychatroom.com/f17/furnace-starts-then-shuts-off-tries-again-128265/)

rrlvm 12-31-2011 02:53 AM

Furnace starts then shuts off and tries again
 
Hi, I have a 1992 Olsen Natural Furnace MOD# MM0802C
The problem is the furnace starts normal, the thermostat calls for heat the inductive fan comes on,the gas valve clicks, the igniter lights the pilot,after a few secounds, the main burners light ( nice and blue) and the blower runs, then it shuts off and tries again and sometimes it starts on the 3rd time and sometimes it tries until it locks out. This is what has been done so far:

1) Cleaned the flame sensor with Emery paper. (most common problem)
2) Checked all the screw's around the bracket of the flame sensor to ensure a good ground. Also ran a separate ground to where flame sensor mounts, to check for good ground. ( I took the test wire off)
3) Replaced igniter
4) Checked intake motor and flume for proper operation.
5) Removed hose to air valve and checked for leaks, and checked to make sure switch was opening.
6) Checked all connections for tightness and corrosion.
7) Checked Inductive Fan Relay didn't have any burnt or dirty contacts. clean contacts anyways. I can see the contacts close, then of course open when the furnace shuts off. I think this is my problem, the Inductive Fan Relay, but there isn't any signs of it being bad?? Maybe I might have to give in to $120.00 hr??

Any help would be very appreciated. Thanks in advance

Houston204 12-31-2011 03:02 AM

I'd measure flame rectification (millionths of an amp) and vacuum at the pressure switch (inches water column).

biggles 12-31-2011 05:28 AM

jump R to W down at the furnace want to see if it's the stat or the wires up to it...should get a consistant cycle till jumper is removed...

sleepyg 12-31-2011 07:48 AM

Check the t'stat, I had one go bad and worked for A/C but not heat. If you have replaced the t'stat recently you need to make sure you have the jumpers set for your application. Look for any bad or loose connections at the burners, if you lose the ground the igniter will not work correctly.

yuri 12-31-2011 08:08 AM

post a pic of the burner section and ignition control. when you replaced the "igniter" what was that? If it has a S86 ignition control U have a pilot burner and igniter combo. at 20 yrs old that gets corroded and warped and needs replacing. also have to clean down to bare metal where it attaches to the furnace and run a green ground wire from one of the screws back to the ignition module mounting plate. ICG had that as a standard feature. if all fails then you may need a new S86 control or possibly the gas valve is failing and dropping out. at 20 yrs old I would not spend any money repairing it by paying someone as the control and valve etc will all start failing soon. we had lots of them where I am but less than 5% are still running. Olsen went bankrupt and the ventor fan is almost obsolete.

The "new" Olsen co bought the name and makes oil furnaces and not parts for yours.

harleyrider 12-31-2011 11:13 AM

Quote:

Maybe I might have to give in to $120.00 hr??
WOW...they work cheap in your area.......

Like Houston said......to truly diagnose your issue, we have to know what the flame signal from the flame sensor to the ignition control is.......


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