York Heat Pump: ERC

Re: Cooling - Control Board Lockout

The Time & Temperature Defrost Board on this heat pump will "Lockout" on a Hi-Pressure Switch trip.

CHECKOUT:

1. Reset & Check Operation

• 2 Ways to Reset
  • Jump the Test pins on the Defrost Board
  • Remove and re-connect "R" and "Y" from the Defrost Board.
• Restart the unit and observe operation.
  • Unit Won't Restart → Step 5. Check Pressure Switch
• Ensure that the fan motor starts and runs normally.
  • Fan Motor Start Normally → Step 3. Check Refrigerant Pressures
  • Fan Motor Doesn't Start → Step 2. Check Condenser Motor

2. Check Condenser Motor

• Check Capacitor
  • Turn off power to the unit by pulling the disconnect or turning the breaker off.
  • Test Capacitor
    • Less than 80% of rating = Bad Capacitor
• Check Motor
  • Check motor bearings by spinning the fan blade.
    • Motor Won't Turn or Stiff = Bad Condenser Motor
  • Re-apply power to the unit.
  • When the compressor contactor energizes, check for 230V to the motor between "C" or "COM" at the capacitor and the Black motor wire.
    • Power but No Motor Operation = Bad Blower Motor
    • No Power = Unit may be in Defrost → Step 4. Check Defrost Stat

3. Check Refrigerant Pressures

• Hook-up refrigerant gauges to the pressure ports on the unit.
• Monitor pressures as the system operates.

• Normal Pressure Range
  Refrigerant	55-75 Deg O/D	75-95 Deg O/D
  R-22	55-70 Suction 150-225 Discharge	55-80 Suction 175-270 Discharge

  • Pressure Switch Trips + Normal Pressures = Bad Pressure Switch.
  • Normal Pressures →Step 4. Check Defrost Stat
  • High Head Pressure ⇒ Check Sub-Cooling
    • Allow the unit to run for at least 10 minutes.
      • Pressure exceeds Normal Range in the first 5 minutes = Refrigerant Overcharge or Restriction
      • 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.)

4. Check Defrost Stat

• At the defrost board, remove the two wires attached to the "Stat" terminals.
• Check resistance through the defrost thermostat.
  • Stat Open = Ok
  • Stat Closed = Stuck Defrost Stat
    • Heat Pump will attempt to enter a defrost mode while cooling (stops outdoor fan & energizes heaters).

5. Check Pressure Switch

• Disconnect the two wires from the defrost board "Switch" terminals.
• Check resistance through the safeties.
  • Pressures Normal + Open Safety = Bad Pressure Switch