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    01Hokie's Avatar
    01Hokie Posts: 4, Reputation: 2
    New Member

    Mar 19, 2007, 11:45 PM
    Replaced thermostat - no heat or a/c
    Hello - I have an Amana a/c with gas heat

    Took out my old Honeywell T8195 thermostat to replace with the Lux TX1500

    Wired it up as follows (Lux - color - Honeywell)

    RH - Red - R
    RC - connected to RH terminal
    G - Green - G
    Y - Yellow - Y
    W - White - W
    B - empty
    O - empty
    Have the blue wire left which was connected to the C on the old one

    Turned it on and got the a/c going immediately. Good news.

    Turned on the heat and waited patiently... nothing happened. Bad news.

    Genius friend tries to switch out the white and blue wires (I wasn't sure I labeled these correctly at the time... now I'm sure the above is correct). Again - no heat. Then - no a/c. Really bad news.

    Hooked the old thermostat up and again no heat or a/c. Really really bad news.

    How deep am I in here? Fortunately hovering around 70 here the next few days so I can keep the windows open until the weekend.
    ballengerb1's Avatar
    ballengerb1 Posts: 27,379, Reputation: 2280
    Home Repair & Remodeling Expert

    Mar 20, 2007, 08:03 AM
    Old stat and no heat? really bad news. Check your line coming into the stat for 24 vac.
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 20, 2007, 08:40 AM
    Likely the blue was a common needed to power the old thermostat. When you connected it to the white and called for heat, you would have a dead short across the 24 V transformer. Look for a blown fuse on the control board or inline. No fuse and the transformer may have died.

    Is this a heat pump? See the sticky at the top of the forum.
    01Hokie's Avatar
    01Hokie Posts: 4, Reputation: 2
    New Member

    Mar 20, 2007, 09:47 AM
    Thanks - I'm praying it's a blown fuse. Didn't have time to go up there and find out last night. The unit is in the attic and my ladder is too short to get up there. Just moved into my first home and jumping into my home improvement head first... fortunately during the cool season.

    This is forced air gas heat.

    When I get up there - how can I verify that the white is the heat before I try and wire it up again... assuming it's a fuse. If it's not a fuse I'm assuming I don't want to get into replacing a blown transformer, correct?
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 20, 2007, 10:49 AM
    The wire from the thermostat should disappear into the furnace near the panel you remove to access the filters. Once open, you should see the wires connecting to a circuit board. The terminals should have the same R, W, Y, C, and G labels as the thermostat and the corresponding colors of wire.

    Even if you smoked the transformer, they are still fairly cheap and easy to replace.

    While you have the furnace open, look at the filters.
    01Hokie's Avatar
    01Hokie Posts: 4, Reputation: 2
    New Member

    Mar 20, 2007, 10:08 PM
    Ok - it was definitely the fuse. It was completely busted. Now the challenge of finding a 24vac 3amp fuse. Radio shack was useless on that one...
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Mar 21, 2007, 05:54 AM
    Most of those are the automotive style blade fuses. If you found one that was only 3 amps, it would be fine. May have to hit a HVAC or electrical supply.
    01Hokie's Avatar
    01Hokie Posts: 4, Reputation: 2
    New Member

    Mar 21, 2007, 09:29 PM
    WOOHOO! I've got a new fuse, new thermostat, and AC... and the heat works, too, for when I need it (which is rare in SoCal)!

    Thanks everybody. My first home... and now my first home improvement screw up. I learned a lot and appreciate the help.

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