Results 1 to 2 of 2

Thread: Thermostat RTH9580WF with Venstar Add-a-wire - AC won't turn on

  1. #1
    Junior Member

    User Info Menu

    Question Thermostat RTH9580WF with Venstar Add-a-wire - AC won't turn on

    Hi All,

    I installed a Honeywell RTH9580 over the winter. I had a 4-wire system and ended up buying a Venstar Add-A-Wire module to provide a Common wire. I installed everything and triple checked my work. The thermostat powered up and the heat & fan worked fine all winter. Now that summer is upon us I tried to test the Air Conditioning since it was too cold to test it in the winter and it will NOT engage. The Thermostat shows the "Cool On" status and clicks so it looks like it is engaging but the AC compressor nor the fan kick in.

    I have a home built in 2013 with forced air (Goodman gas furnace and Goodman AC mounted outside of the house). I just finished taking everything apart again and double checking my connections, still no luck.

    I'm hoping some of you might be able to provide me with some help. I've tried scouring Google for hours without any luck. Most sites just show the Venstar module being hooked up for heating only systems.

    I appreciate any and all help.


  2. #2
    HVAC Thermostat Specialist

    User Info Menu

    Here are a couple test you can try.

    Test 1: At the RTH9580 jumper the R, G and Y together and see if the cooling energizes. If the cooling energizes with the wires jumpered there is an issue with the RTH9580.

    Test 2: If the cooling does not energize in test 1 reconnect the wires to the RTH9580. At the indoor air handing unit jumper the R, G and Y wire together and see if the cooling energizes. If the cooling energizes with the wires jumpered together at the indoor air handling unit there may be a issue with the Venstar Add-A-Wire wiring or the wiring between the Venstar Add-A-Wire and the wall thermostat. If the cooling does not energize in test 2 there could be many things that could prevent the cooling from running here are a few:



    The breaker to the outdoor condensing unit could be off.
    There may be a blown line voltage fuse at the disconnect.
    The AC may be out or low on refrigerant.
    The compressor contactor in the the outdoor condensing may be bad.
    the list go on and on you may need to call a HVAC professional to check the unit.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •