Want heat? On furnace why is w- C and other W -W? ?

TSTAT has a red jumper RH to RC. So I put B=C

G=G  W=W R = R ( took out jumper) 

It’s only blowing cool are not AC cool but not hot


Why are B & R capped off? I had a NEST but it sucks. So trying to switch back. Could’ve the installer done that. 

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5 Answers

  • GTB
    Lv 7
    8 months ago

    Restore the jumper; on very old models you need to separate these two (one is voltage to drive the AC circuit, the other is to drive the Heat circuit) and you had different voltage sources for AC and for heat; in the past 20 years or so you have one voltage source for both AC and Heat so the 2 (Rh and Rc) use the same voltage source; secondly you need to either read and understand exactly how the thermostat circuit works and understand how to use a volt meter for troubleshooting. If these parts are beyond you, then get help.

  • Anonymous
    8 months ago

    1.  Put the jumper back in.

    2.  Call a repairman who knows what the heck he's doing.

  • elhigh
    Lv 7
    8 months ago

    Put the jumper back in.

  • Droopy
    Lv 5
    8 months ago

    I'd say you need that jumper. Old furnaces used millivolts instead of 24 volts for control an thats when you would remove that jumper. But based on the picture you have of that circuit board I'd say you need 24 v Heating an cooling.  Also if you have a extra wire in the wire from furnace to thermostat you can hook it to the C on that board and the C on the thermostat an you will not need batteries in the thermostat. 

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  • 8 months ago

    Most systems require the jumper. The jumper provides common power to both the heating and the cooling side. One only removes the jumper when the system has separate power source for the heating and cooling.

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