St Croix Afton Bay - High Limit Switch

[cssulliv]

Problem - The stove runs very, very hot! I can't run it on Level 3 for too long or it will shut down and "smoke out". So, I am running it on Level 2 and it still runs too hot, IMO. In the past I have run it on level 4 with no problems.

Stove is very clean. The room fan has been removed and cleaned as well as the exhaust fan, etc.

Here is what I have diagnosed so far. There are two wires going into the HLS. One wire controls the auger and one controls the room fan. It looks like the room fan is only running on the low setting causing the stove to run hot and eventually overheat.

The HLS is the manual re-set type and the button is currently in the out position. Per the manual, it should be a closed switch (I assume this means pushed in) When I press the button on the HLS it won't stay in. It will remain in the out position. Also, when I press it in the room fan will kick into a higher gear and blow faster but that also kills the auger.

Per the manual - " This is a “Normally Closed” switch and is part of the Fan limit control. If the High limit switch trips several times, the problem in the Stove must be diagnosed before the Stove is put back in service, (Defective Room Fan, dirty Room Fan, defective Fan Limit Control or possibly a bad Control Board)"

Is there anyway to test the HLS if I pull it out? Also, not really sure how to trouble shoot the Fan Limit Control. Any suggestions on that?

Thanks!

 

[krooser]

Have you cleaned out behind the firebox thru the ash traps? A stove plugged with ash will heat up and trip that switch… you also need to clean out under the combustion fan… I usually remove the housing and dig any crud out in the passage from the burn pot, too.

 

[Don2222]

Hello

If you put an ohm meter on the 2 terminals of the hi limit switch then the meter should real zero or short circuit. If it does not then it is defective.

 

[bbfarm]

I just went through this a week ago. You can go back a few pages for my thread with photos

How well did your fan blades spin when you took it out for cleaning? Did it spin freely or was there some drag?

If you pull the 2 wires off the high limit switch and run a jump wire between them it will show you if the switch is bad. Do not run your stove this way. You need that switch as a safety in case your stove overheats

Did you get all the crud out from under the fan?

See photos

 

[cssulliv]

The stove is clean....very clean. The fan blades spun fine. I was impressed how well they worked since the stove is almost 10 years old.

bbfarm - what was causing the problem you had....bad exhaust fan or bad switch?

don2222 - I will do the ohm test and report back.

Thanks!

 

[cssulliv]

Just tested the switch with my ohm meter.....it reads anywhere from 0.5 all the way up to 8.5.....bounces around....can't get a steady reading but it's definitely not 0.

 

[bbfarm]

Ours was the switch.