Knowledgebase

Yorkguard - Flashing Code 5

Article ID: 488
Last updated: 06 Feb, 2023

York Heat Pump: EFH

Re: Flashing Code 5

Code 5 - Defrost Fault (Going into defrost too often).

These units use a Yorkguard Demand Defrost control board. The board uses an Ambient (outdoor) Sensor and Liquid Line Sensor to determine the proper conditions for defrost to occur.

► If the board senses that the coil temperature sensor is getting too cold, too quickly, and requiring defrost too often - a Code 5 is generated.


Qty Possible Causes:
1 Bad Liquid Line Sensor
 1 Bad Condenser Fan Motor
Bad Fan Capacitor
  Bad Defrost Board
1 Mis-Located Sensor
Low Refrigerant Charge
Bad Expansion Valve


CHECKOUT:

1. Check Outdoor Fan

  • Inspect the outdoor unit and make sure the outdoor fan is operating (if the compressor is not running, you can test by manually pushing-in the contactor).
    • Fan Operating → Step 2. Test Defrost Cycle
    • No Fan ⇒ Check for 230VAC to the fan motor between the Purple and Black wires.
      • No Power = Bad Control Board or Unit in Defrost
      • Power + No Fan Operation = Bad Fan Motor or Capacitor ⇒ Check Capacitor

2. Check Defrost

  • Yorkguard V
  • With the outdoor unit running in HEAT mode, Jump the two "TEST" pins on the outdoor unit control board.
    • If the outdoor (ambient) temperature is below 50 deg. the unit should enter a defrost mode.
  • Ensure that the outdoor fan shuts-off and the reversing valve switches to cooling mode.

3. Check Liquid Line Sensor

  • Disconnect high voltage power from the unit by pulling the service disconnect or turning the breaker off.
  • Disconnect low voltage from the defrost board by removing the Red, "R" wire.
  • Sensor Resistance
  • Disconnect the two wires from the defrost board connected to "LL".
  • Set the multi-meter on 200K Ohms.
  • Test resistance of the sensor.
  • Use Resistance Chart to determine sensed temperature.
    • If sensed temperature is more than 5 deg. higher or lower than the actual temperature = Bad Liquid Line Sensor
  • Sensor Location
  • It is very common for technicians to put the liquid line sensor in the wrong location (which can cause the unit to terminate defrost before the coil is thawed).
  • The sensor must be located on the condenser coil side of the metering device, as close to the metering device as possible.
    • With an expansion valve, it is possible to mount the sensor between the valve and the coil distributor.
    • With an orifice, the proper location is typically where one of the distributor lines ties into a short 3/8" piece of copper at the coil.

4. Check Ambient Sensor

  • Disconnect high voltage power from the unit by pulling the service disconnect or turning the breaker off.
  • Disconnect low voltage from the defrost board by removing the Red, "R" wire.
  • Disconnect the two wires from the defrost board connected to "OD".
  • Set the multi-meter on 200K Ohms.
  • Test resistance of the sensor.
  • Use Resistance Chart to determine sensed temperature.
    • If sensed temperature is more than 5 deg. higher or lower than the actual temperature = Bad Ambient Sensor
      • Ambient Temperature reading less than 50 deg and the board will not initiate defrost = Bad Defrost Board

5. Check Refrigerant Pressures

  • 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.
Normal Pressure Range
Refrigerant 0-30 Deg O/D 30-50 Deg O/D
R-22
  • 20-45 Suction
  • 175-225 Discharge
  • 40-55 Suction
  • 180-250 Discharge
  • If a Liquid-Line Sight Glass is installed, observe for bubbles in the sight glass (after the system has been operating for at least 5 min.)
    • Bubbles = Low Refrigerant Charge
  • Low Pressure Issues
    • Low Suction + Low Discharge + Bubbles in Sight Glass + Expansion Valve Frosting = Low Refrigerant Charge
      • Try adding refrigerant through the Low Pressure gauge.
        • Suction and Discharge Pressures should gradually increase as refrigerant is added.
        • If the Discharge Pressure increases but the Suction stays low or drops = Bad O/D Expansion Valve
    • Low Suction + Low Discharge + Clear Sight Glass + Expansion Valve Frosting = Bad O/D Expansion Valve 
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Article ID: 488
Last updated: 06 Feb, 2023
Revision: 6
Views: 337
Comments: 0