Harman P68 trouble with thermostat

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New Member
Oct 10, 2023
My p68 has been a steady workhorse up until when I started it up this season. The room temp probe has failed. My meter reads all open, no resistance reading so I replaced it. The new one I was given varied on it's resistance reading around 3k ohms depending on temp. I installed the new probe and now the status light will not illuminate at all. If I have the stove working on room temp, it will act like it's going to start up and then turn off within about five seconds of of the dial being moved out of the off position. I am not getting any blinks on the status light at all in room temp position. I moved the dial to constant temp and had the "temp" dial set to 60 degrees, my house was quite chilly. The stove ran all night, not cycling off at all. The house was quite toasty but I can't keep running the stove like this. It's current condition seems unsafe. I have the feed turned down to like 1, not recommended, to help keep the heat down but then the stove burns too far back into the pellets and I'm afraid that I'm going to catch the hopper on fire. I hope I'm giving enough information for assistance on solving this issue. I can't seem to find much on line that's anything other than dealing with light codes that are covered in the manual that comes with the stove. Does anyone know of a wiring diagram that could be available? I think there is some thermostat on the board that might be having trouble but I'm not sure how to narrow it down. Thanks in advance for any assistance.
Let me add that the stove and all lights work in "test". I'm going to play more tonight and I'll post more if I discover anything new. I did find a wire diagram and assembly breakdown on line. I think that will be very helpful. Has all the part names and numbers, very nice to have.
I may not have a solution to your issue, but I can tell you that running it on cp0nstant with a low feed rate is fine. I do that in the deep of winter.

Try moving the temp dial up to 70 and see if it runs. You may have a "flat" spot. My P61a developed a flat spot and it threw it way out of whack as far as starting temp went.