Climatemaster Geothermal: Heating 

Re: Code 2 / High Pressure Fault

Code 2 = High Pressure Fault

When the high pressure switch opens due to high refrigerant pressures the compressor relay is de-energized immediately since the high pressure switch is in series with the compressor contactor coil.

CHECKOUT:

1. Check Indoor Airflow

• Set the thermostat to call for heat.
• Confirm that the indoor fan is operating and air is blowing out of the supply registers
  • No Airflow → Step 2. Check Blower Motor
  • Airflow → Step 3. Check Operating Conditions

2. Check Blower Motor

• These units use with a Variable Speed Indoor Blower.
• Confirm that 240VAC is being supplied to the motor.
• Confirm that 24VAC is present between "C" and "G", "Y1" or "Y2".
  • No 24VAC power = No signal from thermostat
  • 240V Power Present + 24V Power Present + No Blower Operation = Bad Blower Motor or Bad CFM Board

3. Check Operating Conditions

• If the heat pump is in lockout, reset by removing 24VAC power to the control board.
• Ensure that the unit is running at full capacity (Y1 & Y2 Energized).
• Unplug the 3-wire heater connector from the control board to temporarily prevent aux heater operation.
• Allow the unit to operate for at least 5 minutes.
  • If the unit kicks-off on Hi Pressure safety in the first 5 minutes = Bad Overcharge, Refrigerant Restriction or No Airflow
  • If the compressor never kicks on & the control locks-out on High Pressure ⇒ Suspect a Bad Pressure Switch
• Unplug the HWG pump motor (if the HWG piping is hooked-up and active).
• Check and record the Water Pressure Drop through the geo-thermal unit.
• Check and record the Entering Water Temperature and the Leaving Water Temperature.
• Check and record Refrigerant Pressures.
• Calculate Subcooling.
  • High Pressure GaugeTemp - Liquid Line Temp = Sub-Cooling
• Check and record the Air Temperature Rise through the unit.
• Compare operating conditions to Unit Performance Chart.
  • High Subcooling + High Dicsh Pressure + High Suction = Overcharged
  • High Subcooling + High Disch Pressure + Low Suction = Bad Expansion Valve
  • Low Subcooling + High Disch Pressure + High Air Temp = Low Indoor Airflow or Heat Transfer → Step 4. Check Air Filter & Indoor Coil

► Be sure to re-connect the 3-wire heater plug and HWG pump before closing the unit.

4. Check Air Filter & Indoor Coil

• A dirty air filter or indoor coil generally won't cause a Code 2 due to the nature of a V/S blower unless badly clogged.
• Remove Air Filter and Check for a Dirty Indoor Coil
  • If the Indoor Coil is OK --> Re-Check Temperature Rise with the filter removed.
    • No Change = Restricted Ductwork or Low Blower Speed → Step 5. Check Duct Static Pressure
    • Temperature Rise Becomes Normal = Clogged Air Filter ⇒ Replace Filter & Re-Check Pressures

5. Check Duct Static Pressure

• High duct static generally won't cause a Code 2 due to the nature of a V/S blower unless badly restricted.
• Check the return duct static pressure.
• Check the supply duct static pressure.
  • High Static = Above 0.5" w.c.
    • High Return Static + Low Supply Static = Restricted Return Ductwork
    • Low Return Static + High Supply Static = Restricted Supply Ductwork
  • Static Pressure Normal ⇒ Increase Blower Speed or Clean Blower Wheel