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    paxfax's Avatar
    paxfax Posts: 1, Reputation: 1
    New Member
    		  
    #1

    May 24, 2008, 09:53 AM
    Thermostat Wiring Issue
    I have a very common split A/C HVAC system. It has a 5 wire thermostat which I replaced recently with a new digital unit. (LUX9000) I have hooked up the wires according to the manual in a 5 wire system.
    Y G W B R (AC Comp - Fan - Heater - Heater XFRMR - A/C XFRMR)
    However, when I turned on the A/C, it did not work. So I switched the RH and RC wires.
    Then it worked great. Then it got cold... and I switched it to heat... and not it did not work.
    So I switched RH and RC back... and of course now the heat works.
    I know I have done something wrong... but need help figuring it out. I have two 2.5 ton units that are identical... purchased 2 of these thermostats and wired them identically... and the issue is identical with both, so it is not a faulty thermostat or FAU. Please advise. Cheers: JP
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #2

    May 24, 2008, 04:35 PM
    Sorry but I have no info on LUX thermostats.
    eschuen's Avatar
    eschuen Posts: 62, Reputation: 6
    Junior Member
    		  
    #3

    May 25, 2008, 06:11 PM
    Look at your old t-stat.. did it have a jumper between RC and RH this might be the problem... just a guess since cannot see how the old was wired.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
    Uber Member
    		  
    #4

    May 25, 2008, 06:12 PM
    Jump Rc to Rh and it will be fine.
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