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The main HVAC unit in my house is set up on two zones, the main part of the house and the master bedroom, using the Honeywell HZ322 panel. It's a little over five years old. About a week ago the heat stopped working in the master bedroom but was still working fine in the main part of the house. Calling for heat from the bedroom would blow cold air but emergency heat was working. I've tried three different thermostats but the problem has been unchanged. The exact symptoms have been changing and at a couple points the heat started working again for a while. I went under the house and was able to operate everything normally from the controls on the zone panel but I discovered that when the thermostat calls for heat "cool" was lighting up and I could hear the compressor come on. At that point the thermostat was blinking heat on, then solid heat on, then auxiliary heat came on and then the system would turn off. Now, it goes through the same sequence on the thermostat but the system never turns on and the thermostat never turns off but continues to say heat on and auxiliary heat on. Has my board gone bad?

Thanks!

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To figure out if your Honeywell control board is bad, I would swap the two zones' wiring and see if that makes the heat work in the master bedroom but becomes broken in the main part of the house. Make sure you disconnect the power before you work on anything.

Label and disconnect your zone 1 damper and zone 1 thermostat wires, and connect them to zone 2. At the same time label and disconnect your zone 2 damper and zone 2 thermostat wires, and connect them to zone 1. Taking a picture might help if you get confused later.

This board should be able to control 4 zones, so if zone 1 or 2 is broken you may still be able to switch it to zone 3 or 4 on the board and not need to replace the control board.

If swapping the zones doesn't do anything, I would check if the thermostat wiring is bad. Connect your master bedroom thermostat directly to the Honeywell control board and see if that fixes it. If the problem stays the same, then we at least know it's not your thermostat wires when we continue troubleshooting.

Honeywell HZ322 Zone Panel Professional Installation Guide

Fig. 11. Zone panel wiring—conventional

  • I will take your advice and see where that leads me. Thank you! – dev_willis Dec 12 '17 at 3:32

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