CHECKOUT:

1. Check Unit Status

• Set the thermostat to call for heat.
• Inspect the geo-thermal heat pump to see if the compressor is operating.
  • Compressor Operating --> Step 3. Check Loop Water
• Check for 24VAC between "Y" and "C" on the unit control board.
  • No Power = No Call from the Thermostat --> Check Thermostat
  • Power Present--> Compressor should start within 5 minutes.
    • Check the control board for active Diagnostics.
      • LED Flashing = Control in Lockout due to active diagnostic --> Short TEST pins to show diagnostic code.

2. Check Compressor Operation

• Compressor Hums but Doesn't Run = Bad Capacitor, Locked-up Compressor, or Burnt Compressor Wiring
• Compressor Does Not Try to Start --> Re-Check for 24VAC between "Y" and "C" on the control board.
  • No Power = No Call for Compressor --> Re-check Thermostat
  • Power Present + No Diagnostics + 5 Minute Delay + No Contactor = Bad Control Board or Bad Contactor
    • Check for 24VAC across both contactor coil wires.
      • Power present but contactor doesn't pull-in = Bad Contactor
      • No Power --> Suspect Bad Control Board

3. Check Loop Water

• Pumps
• Use an Amp Probe to check amperage on each loop pump to ensure that they are operating.
  • Pumps should start with the compressor.
  • Each pump should draw .7 to .8 amps.
• Pressure Drop
• Use a Pressure Gauge to check the water pressure drop through the unit.
  • Use performance chart to calculate and record the GPM/Ton.
    • No Pressure or Negative Pressure = Low Water
• Temperature Drop
• Use a thermometer to check the water temperature drop across the unit while the compressor is operating at full capacity.
  • Check and record the inlet water temperature.
  • Check the outlet water temperature.
    • Calculate and record the water temperature drop.

4. Check Refrigerant Pressures

• Hook-up refrigerant gauges to the pressure ports on the unit.
  • Blue --> "True Suction" Low Pressure
  • Red --> High Pressure
• Place an insulated temperature sensor on the liquid line between the evaporator coil and expansion valve.
• Monitor and record the pressures as the system operates.
• Calculate and record the "Sub-Cooling".
  • Check "Saturation Temperature" from the discharge pressure gauge.
  • Subtract the Actual liquid line temperature reading.
    • Sub-Cooling = Saturation Temp - Liquid Line Temp

• (Split-Systems) If a Liquid-Line Sight Glass is installed, observe for bubbles in the sight glass in-lie of checking sub-cooling (after the system has been operating for at least 5 min.)
  • Bubbles = Low Refrigerant Charge

5. Check Air Temperature Rise

• With the auxiliary heaters disconnected (remove "W" from the low voltage terminal block):
  • Check the Return Air Temperature near the unit or in the filter compartment.
    • Abnormally Low Return Air Temperature --> Check Return Ductwork for Cold Air Infiltration
  • Check the Supply Air Temperature.
  • Calculate and record the air temperature rise.
  • RE-HOOK THE "W" WIRE ON THE CONTROL BOARD.

6. Check Thermostat Aux Settings (New VisionPro 8000)

• Check the Aux Heat Control Setting
  • Under Installer Setup, go to Setup #301
    • Change from "Basic" to "Advanced"
  • Press Next to advance to Setup #309 - "BACKUP HEAT DROOP"
    • Change from "comfort" to "2.0" or "3.0"
  • Press Next to advance to Setup #311 - "UPSTAGE TIMER FOR BACKUP HT"
    • Make sure value is set to "Off".
  • Press Done to save changes.
    • This change doesn't allow Aux Ht operation unless the indoor temperature drops [#309] degrees below setpoint.