York Heat Pump: Yorkguard IV & Yorkguard V

Re: Flashing Code 2 (Cooling)

Code 2 = High Discharge Pressure

If the Hi Pressure circuit input on the Yorkguard opens, the module will go into a Code 2 lockout and disable compressor operation.

CHECKOUT:

1. Check Unit Operation

• Set the thermostat to call for cooling.
• Allow 5 minutes for anti-short-cycle delay or jump Test pins (Yorkguard V only) to bypass timer.
• Observe the outdoor unit to ensure that the compressor and condenser fan motor start.
  • Unit Starts and Runs Normally → Step 3. Check Refrigerant Pressures
  • Unit Doesn't Start ⇒ Check Control Board Diagnostic Light
    • Flashing Code 2 = Still Locked-Out
      • Reset by removing and reconnecting "R" and "Y" at the o/d unit control board for at least 5 seconds.
  • If the control board re-enters Code 2 without starting the compressor = Bad Pressure Switch

2. Check O/D Motor & Capacitor

• Check Capacitor
  • Turn off power to the unit by pulling the service disconnect or by turning the breaker off.
    • Use a multi-meter to confirm that voltage is not present.
  • Remove capacitor wires (short before touching)
  • Move Multi-Meter leads to COM and MFD.
  • Set Meter to 200 MFD.
  • Place one lead on "C" or "Com" of the capacitor and the other on "Fan".
  • Confirm MFD reading with capacitor rating.
    • Less than 80% of rating = Bad Capacitor
  • SWITCH METER LEADS BACK TO COM AND V BEFORE PROCEEDING!
• Check Motor
  • Re-apply power to the heat pump.
  • Set the thermostat to call for cool.
  • Check for 24VAC from "Y" to "C" on the low voltage wiring.
    • No Power = No call for cool from the thermostat.
  • When the compressor contactor energizes, check for 230V to the motor between "C" or "COM" at the capacitor and the Black motor wire.
    • Power + No Motor Operation = Bad Blower Motor
    • No Power = Bad Defrost Relay (Yorkguard IV) or Bad Control Board (Yorkguard V)

3. Check Refrigerant Pressures

• If the heat pump is in lockout (still flashng a code), reset by cycling 24VAC power to the outdoor control board (remove "R" and "Y" or cycle power to the air handler).
• Hook-up refrigerant gauges to the pressure ports on the unit.
  • Blue --> "True Suction" Low Pressure
  • Red --> High Pressure (either refrigerant line)
• Monitor pressures as the system operates.

• Pressure switch trips immediately or while discharge pressure is in a normal operating range = Bad Pressure Switch.

• High Pressure Issues
  • Place an insulated temperature probe on the liquid line between the outdoor unit & indoor expansion valve.
  • Allow the unit to run for at least 10 minutes.
  • Monitor pressures and temperature as the system operates.
    • If pressure exceeds Normal Range and kicks-off on Hi Pressure safety in the first 5 minutes = Refrigerant Overcharge or Restriction
  • Check Sub-Cooling
    • Record "Saturation Temperature" from the discharge pressure gauge.
    • Subtract the Actual liquid line temperature reading.
      • Saturation Temp - Liquid Line Temp = Sub-Cooling
      • Sub-Cooling > 13 deg. + High Discharge + High Suction = Overcharged
      • Sub-Cooling > 13 deg. + High Discharge + Low Suction = Bad Expansion Valve
      • Sub-Cooling < 2 deg. + High Discharge = Low Outdoor Heat Transfer (Dirty Coil, Wrong Fan Blade, etc.)