I have a Honeywell EMM-3 Electronic MiniZone Panel and my thermostat is set at 78 degrees but the house is registering at 89 degrees and it won't cool down although the a/c has been on all day for days. Zone 3 is not lit up but all the other Zones are. I know this has something to do with it being so hot. What does Zone 3 do or regulate and is there a way that I can reset it?

On the thermostat, the two temp readings are showing two different settings, one is the setting temp that you are selecting, and the other is the room temp.

AC means "air conditioning." If the AC icon is showing on your thermostat it means that your air conditioning is activated and should come on when the temperature threshold you've set on the thermostat is reached.

For example, if you've set the temperature level to 78 degrees, when the house temperature goes above 78, usually by about two degrees, the air conditioner should cycle on to cool it back down to 78 degrees at which point it will then turn off.


This information should be in your air conditioning/heating system or thermostat owners manual. If you don't have the manual, you should contact your air conditioning dealer or your builder to secure a replacement. The manual is essential for proper operation and maintenance of your system.

Replace it (thermostat), but first make sure its in a good location to read the space temperature.

Hi, Either push the program or resume program button... or on some you need to push the hold button again to take the hold off... Check the manual if all of this does not work... but the t-stat may be fried...

Here is a tip that tells you how to get a manual for most any Honeywell productonline...

Manual Honeywell How to Find Honeywell Manuals

heatman101

go to Honeywell web sit with correct and full m# look for instruction man

What is the model number of the thermostat? What may be happening is the humidity control is trying to satisfy the humidity setting by running the a/c. In the installers set-up, there should be a setting to determine how long the system should run to satisfy humidity setting. I typically set thermostats for a 3 degree droop. Meaning it'll only drop 3 degrees below set temp. Also check your humidity setting to be sure it's not set too low. It should be set between 45% and 50%.

Actually that thermostat is adjustable for only +/- 1 degree. I would make sure it is located close to a radiator/register, whichever you have, to help close that 8 degree variance. The thing about hot water heat is that even when the boiler shuts down those radiators are still putting off heat, so the temp can still shoot up a few more degrees after the stat has been satisfied. Is the boiler shutting down when the stat hits 71* ? If not then the stat may be bad. Honeywell carries a 5 year replacement warranty on that stat. I use the Honeywell Focus stats in almost all my installations. They are a very dependable thermostat. Feel free to ask anything else that will help solve your problem...Rob

sounds like a furnace problem - the zone control sounds right

Nothing is wrong; the air circulation in the room affects the thermosistor slightly in your thermostat, so does shade/heat etc.

Try changing the batteries.