NCM 300 Zone 1 stopped working

[gurban]

OK, here's the situation. Bear with me for a minute. Unit has been functioning properly for a long time. All that was done was pulling a Nest (2nd gen) unit off of the base in order to patch and paint around the unit. No wiring has changed. Once replaced, the zone stopped functioning properly. Although, it appears that the heat is on, nothing is really on. The other zone (zone 2) remains open as well suggesting it thinks everything is off. If I turn on Zone 2, zone 1 closes suggesting it is off even though the thermostat itself is on. Zone 2 functions properly as far as I can tell. I've tried multiple resets of both the thermostat in Zone 1 and the NCM300 but no luck.

OK, here's the really weird part. If I pull the faceplate again (Nest thermostat off it's base) the air handler and the outside AC unit come on. How is that possible? There are no thermostat wires connected to anything! With thermostat attached and set to off, same thing happens. Air handler and outside AC unit come on. In order to further rule out the thermostat as the culprit, I followed the advice here.

http://www.ryanduell.com/2014/01/furnac ... hermostat/

I took the red and white wires and closed them to see if the heat would come on. Nothing. The unit shuts off. When I open the two again, the air handler and the ac unit kick on. As in the article, even though I was having a different issue (and it seems it is related to the NCM300 and not the Nest thermostat) I did try to disconnect the yellow wire as well but no luck.

I'm not sure what else to try at this point. Any suggestions? A few things I may try.

1) switch zone 1 and zone 2. It is more important that the original Zone 1 works. If I move that to Zone 2 and it starts to work again, it is a temporary win until I can figure out the longer term fix.

2) can zone 1 be moved to zone 3? Right now it is empty. That would then leave zone 1 empty. Not sure if the unit would function properly with zone 1 empty.

Other ideas?

[Paul Z.]

Suggest you call 1-800-446-3110X490, have a few questions.