Author Topic: HVAC problem!  (Read 972 times)


  • Bristles
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  • Posts: 413
HVAC problem!
« on: April 29, 2017, 02:25:05 AM »
Never touched an AC unit before in my life. But OK with live power, and awesome with computers :)

I have a honeywell EMM 3 minizone.

Only zone 1 and 2 are hooked up.

I have not used my AC/Heater/Fan in 3 months and when i attempted to turn it on yesterday nothing happened.

I turned both thermostats back to OFF, waited 12 hours and turned one to COOL. The compressor came on and i had cold air for 10-60mins! But would not come back on.

I used a MM and checked for voltage coming from the thermostats, both are seeing 24v while going from R to WYG.

I jumpered R to G to force the FAN (from what i have red green should be fan)

Fan will not come

I used the "reboot" button on the system. The orange/yellow system light turns yellow, which from what i can tell is a 2.5min purge. After that the light turns off.

I also noticed that zone 3's LED is green, which means all dampers are open? Meaning all zones in the house should be getting air all the time? From my understand that is NOT how the system should be working, they should be off unless they are heat/cool/fan is on?

I am assuming i just have a bad board? Any thoughts or suggestions would be nice...

My next thing to try would be to just wire up the cool signal directly into the AC unit? And bypass the controller? is that something that can safely be done for troubleshooting?

Image of my zone controller layout.

Thanks! Trying to save a 100$ "service" call, + the crazy high hourly rate to just tell me to replace the board.


Followed the built in troubleshooting and made it all the way through, excluding the DATS question, not sure what that is.

Yes i have a few of the DATS on several of the air ducts, guess i will resume the final troubleshooting steps tomorrow.
« Last Edit: April 29, 2017, 03:19:58 AM by MoonLiteNite »