a419 Stuck on Heat

[nouseforanameHussmann]

Hey guys,

This is my first time posting on the site.
Has anyone ever seen an a419 thermostat get stuck on heat mode? The jumper pins are in the correct spot. It was working perfectly on cooling mode, then two days later it is stuck on heat.

[2sac]

If your positive it's the control, replace it.

[nouseforanameHussmann]

Oh yeah, it is definitely the control, and that is my plan. But it just seems really strange that it would randomly switch onto heat, wondering if anyone else has ever experienced that.

[tyv12]

I have seen quite a few do this, mostly in very cold temperatures. I believe it is due to something breaking and shorting out behind the pins if someone moved the jumpers too roughly

[CFESAmasterEGSR]

I had a drawer set at a location trash 3 A419 controls within 6 months. I discovered the back side of the board where the setting pins are soldered t the board, corrosion was occurring causing the pins to short. This was happening on new controls at less than a month old. I talked to Johnson tech line, of course they said it was environmental and not a problem with their units. So on the last one I installed I coated that area of the board with the NSF silicone that I carry. That was 6 months ago.

That's exactly what mine were doing, check the back of the board when you pull it out and silicone the back of the new one where the pins are. The silicone won't hurt anything.