Announcement

Collapse
No announcement yet.

Is it the thermostat???

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Is it the thermostat???

    My neighbor just ran me down and had a problem. His A/C cools fine but when it is brought down to temperature (around 70 degrees) it will not turn off. He says he has to bring push the adjustment up to 85 degrees before it will turn off. Maybe it would turn off at 75 after completing its cycle. I don't know. Just telling you what he describes.

    It's an older mercury switch-slide thermostat. So....

    Is it the thermostat???

    J.C.

  • #2
    Re: Is it the thermostat???

    Try jumping it manually, then break the circuit to see it it turns off.

    Comment


    • #3
      Re: Is it the thermostat???

      Thanks for the reply Duck. But what you just said to me sounds like the teacher on Charlie Brown. Bwah bwah bwah....

      Don't know anything about HVAC.

      J.C.

      Comment


      • #4
        Re: Is it the thermostat???

        Originally posted by DuckButter View Post
        Try jumping it manually, then break the circuit to see it it turns off.
        Originally posted by JCsPlumbing View Post
        Thanks for the reply Duck. But what you just said to me sounds like the teacher on Charlie Brown. Bwah bwah bwah....

        Don't know anything about HVAC.

        J.C.
        Jump the two wires together than separate them.

        Mark
        "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

        I never lost a cent on the jobs I didn't get!

        Comment


        • #5
          Re: Is it the thermostat???

          I know, I know. This is going to be a real dumb question. Which two wires? My thermostat has 5 wires

          J.C.

          Comment


          • #6
            Re: Is it the thermostat???

            The first issue is to use real thermometers when testing the thermostat. The ones on the thermostat do not really mean anything. The second issue would be the thermostat need to be set level on the wall because of the mercury switch. If the thermostat is set crooked on the wall the mercury switch will be off temperature. After you take care of those two issues and you still have a problem then you may want to follow Duckman's suggestion.

            Mark
            "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

            I never lost a cent on the jobs I didn't get!

            Comment


            • #7
              Re: Is it the thermostat???

              Originally posted by JCsPlumbing View Post
              I know, I know. This is going to be a real dumb question. Which two wires? My thermostat has 5 wires

              J.C.
              It's been a while since I have done HVAC but I believe red is power, yellow is compressor and green is fan.

              Mark
              "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

              I never lost a cent on the jobs I didn't get!

              Comment


              • #8
                Re: Is it the thermostat???

                At the thermostat, jumper red to yellow. Or at the compressor there will only be two low voltage wires. You can jumper it there as well. I would bet on a bad thermostat, but the compressor control relay may be bad also.
                sigpic

                Comment


                • #9
                  Re: Is it the thermostat???

                  Originally posted by NHMaster3015 View Post
                  At the thermostat, jumper red to yellow. Or at the compressor there will only be two low voltage wires. You can jumper it there as well. I would bet on a bad thermostat, but the compressor control relay may be bad also.
                  Exactly

                  Comment


                  • #10
                    Re: Is it the thermostat???

                    Originally posted by JCsPlumbing View Post
                    I know, I know. This is going to be a real dumb question. Which two wires? My thermostat has 5 wires

                    J.C.
                    I know for a fact that you have at least an analog voltage tester/continuity tester (shows when a circuit is open or closed without a current).

                    I have one mainly for electric w/h diagnostic, also for boiler work.

                    TT wires are "supposed" to be color coded, but I'd just check for current when the t-stat is on....OR go to the compresser and check the colors there.

                    Comment

                    Working...
                    X