Harmon P43 won’t restart in auto mode

[JRemington]

I looked at a P43 today that is having an issue. In manual mode the stove runs flawless, but in auto mode once it reaches temperature and shuts down it won’t relight. Can some of you Harmon pros point me in the right direction. Thanks.

 

[Washed-Up]

Not a pro…clean the ESP and check the esp wiring…and it’s HARMAN…ehhhhhhh lol

 

[bogieb]

After it shuts down completely, try turning the temp dial up about 5*. If it restarts, most likely there is a "dead spot" where the dial normally resides.

 

[JRemington]

After it shuts down completely, try turning the temp dial up about 5*. If it restarts, most likely there is a "dead spot" where the dial normally resides.

I made a mistake in my original post. It won’t start in manual at all, but it will in auto. It will do one cycle, shut down and then you have to unplug it and plug it back in to start it again. I tried turning up the temperature but it didn’t do anything.

 

[Washed-Up]

Does it shut down if you flip it to manual while it’s running, after it’s lit in auto?

 

[JRemington]

Does it shut down if you flip it to manual while it’s running, after it’s lit in auto?

If I flip it to manual it runs about until it would have come up to temperature in auto and shuts down.

 

[Tonyray]

in manual it should eventually ramp down and simmer for a while just feeding few pellets now/then.
but should NOT shut down or off.. of course u know that so having a harman P series 9 yrs I cannot figure why it is Acting like it's in Room Auto,,can u take picture of your control settings? and, does it run ok on stove/constant mode?

 

[Allclear]

I seem to be having the same issue(s) as the Minister of Fire with my 12-year-old Harmon P43. At first I thought the igniter, which was original, was either weak or intermittently failing. I replaced the igniter, but the issue continues. Up until this year I always used the stove in room temperature mode. It operated flawlessly. The clue that there now is a problem is that the pellet burn pot will periodically overfill with pellets and spill not burned, burning or smoldering pellets into the ash pan. Apparently, the igniter is turning off - as if the stove is shutting down. Once the combustion blower shuts off, the burning pellets laying in the ash pan fill the stove with smoke which then leaks into the room. I find that I must unplug the stove to "reboot" the board if I want to restart the blower/cycle and return to a proper burn process. But, this works best when the stove is cold. I do not appear to have any pellet auger feed or temperature control when in room temperature mode anymore. I have been using the stove now in stove temperature mode these last 30 days. I clean the exhaust sensor thoroughly at the beginning of each heating season. I otherwise clean the stove often. I cannot obtain licensed Harmon service where I live until January 30. The alarm lights do not display any required codes, but I'm hopeful that the technician's monitoring port located on the control board may reveal what device has failed. My pellets are stored on their delivery pallets within my unheated garage. The pellet quality has never been an issue. What I do not want to do is to replace parts with a hit-or-miss approach.

 

[Washed-Up]

Maybe start your own thread…but I would start with the temp probe, check that there’s continuity with it

 

[scajjr2]

I made a mistake in my original post. It won’t start in manual at all, but it will in auto. It will do one cycle, shut down and then you have to unplug it and plug it back in to start it again. I tried turning up the temperature but it didn’t do anything.

OK with the igniter set to Manual the stove can't start from cold so you're "won't start in manual at all" is normal. Set to Auto to start, flip to Manual to go to a low maintenance burn between calls for heat. Leave switch at Auto to have stove shut down and auto relight when next call for heat comes.

You will have to check the exhaust temp sensor probe. It should have the one with red wires, 1000 to 1100 ohms resistance depending on them temp the probe is at when you test it. Resistance should increase when heat applied to it (thanks to an old post by Ssyko for that info). And it's not uncommon for no error codes even if it's going or gone bad. I would check temp probe for correct resistance, bad wire(s) and connection at control board. Also check the room temp probe. Hopefully not a flakey control board.

sam