I have 2 zones, both of which are programmed. The display for zone 2 works fine. When I am looking at zone 1, the desired heating and cooling temps display as -- with no temps there. The system is set on Cool mode and Fan is on auto. Out mode is not selected. Hold mode is not selected. When I go into programming mode, the desired temps show there just fine, but as soon as I go back to normal operating mode, zone 1 only displays dashes for the desired temps.

read manual for setting up temp and time
Press the Set Time/Temp button until the HEAT icon is flashing. Press the up or down button until the desired heating temperature for that period is displayed. If that zone is going to be unoccupied press the Out button.-----------------https://www.northerntool.com/images/downloads/manuals/20390.pdf

That leaves a huge grey area. Help us help you. Are you looking at the zone panel? Is zone 1 upstairs? Does red mean powered when closed or opened? Are other zones cooling? Does zone 2 turn red AND when. Model numbers...

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Change the system selector to cool. Press hold if applicable and then set desired set point.

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

If it 2 degree cooler then that's fine .adjust your thermostat 2 degrees higher so you will get the temperature

you will have to program all of the zones into the wall controller. to access the service parameters turn the controller to the off position then press clock. hold buttons 2 and 4 down for 5 sec then press the mode button it should display
1 01
or something like that u can scroll threw the parameters with buttons 1 and 2 and u adjust the values with the dial. for u it will need to be set to
1 15
1 17
1 18
1 20
2 21
1 23
3 24
this will then make it have all 3 zones so it will display zone A, B, C this is only for heating tho for cooling u will also need to program it in they are different numbers.
Hope this helped

-Chris

turn it on

On the zone damper motor, there should be a little lever allowing you to open the damper for emergency heat. Probably a bad zone motor or connection.

The stat that works is called the main and the other two are called slave stats. The stats must be set to heat or cool the same as the main. If you want one room to cool and one to heat , sorry. Need to upgrade to auto changeover. Is this AC actally a Heat pump?

It is not your thermostat, it is an airbound zone. The gurgly noise you heard was that water and air flowing through the radiator. The zone needs to be purged either at the boiler, or through vents on the radiator. Hope this helps