Virginia Geothermal compressor shuts off after a few seconds, bad pump?

Discussion in 'Maintenance and Troubleshooting' started by inti37, Sep 12, 2020.

  1. inti37

    inti37 New Member

    3.0 ton GeoCool geothermal heat pump
    product #: GCHP01036V-LF-A
    system has been running fine for 3 years

    • in Cool mode, compressor starts for a few seconds, then shuts off
    • air filter is new
    • I see some amps flowing to the external pump, but I don't detect any water flowing thru the ground loop
    • pump seems to be vibrating slightly, but I think this is coming from the main unit through the pipes
    • my best guess is that the 25 year-old pump (Grundfos UP 26-99F) is not working
    • because there is no water flow, the compressor shuts down to avoid over-heating
    • what should I do next to confirm it's the pump?
    Thank you.
  2. geoxne

    geoxne Active Member Forum Leader

    You should check to see if there are any lights lit on the lockout board. This will point you in the right direction to diagnose. Green is High Ref Pressure. Amber is Low Ref Pressure. Red is Flow Switch Water. Yellow is Condensate Overflow.

    If it is the water flow switch it may be the pump or the loop is air bound. High Ref Pressure is also a symptom of low water flow.

    Install Manual
  3. geoxne

    geoxne Active Member Forum Leader

  4. inti37

    inti37 New Member

    Thank you @geoxne, the green power light is blinking, and the high pressure green light is on but not blinking.

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