York Heat Pump: ERA
Re: Not Defrosting / Frozen
The ERA models use a Time & Temperature control board.
The board uses a Coil Thermostat and Timer to determine the proper conditions for defrost to occur (timer adjustable for 30, 60 or 90 minutes).
Qty |
Possible Causes: |
1 |
Bad Defrost Stat |
1 |
Bad Condenser Fan Motor |
|
Bad Fan Capacitor |
|
Bad Defrost Board |
|
Low Refrigerant Charge |
|
Bad Expansion Valve |
|
Bad Reversing Valve |
CHECKOUT:
1. Check Outdoor Fan
- Inspect the outdoor unit and make sure the outdoor fan is operating normally.
- Fan Operating → Step 2. Test Defrost Cycle
- No Fan ⇒ Check for 230VAC to the fan motor.
- No Power = Bad Control Board or Unit in Defrost
- Power + No Fan = Bad Condenser Motor or Capacitor ⇒ Check Capacitor
2. Test Defrost Cycle
- Jump the TEST pins to force the unit into defrost (hold TEST pins until unit enters defrost).
3. 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 |
- 20-35 Suction
- 160-220 Discharge
|
- 36-65 Suction
- 170-260 Discharge
|
- Low Pressure Issues
- Low Suction + Low Discharge + Expansion Valve Frosting = Low Refrigerant Charge or Bad O/D Expansion Valve
- 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
4. Check Defrost Stat
- Disconnect high voltage power from the unit by pulling the service disconnect or turning the breaker off.
- Disconnect the two wires from the defrost board connected to "T-STAT".
- Test resistance of the stat.
- Stat should Close below 30 deg. and Open above 65 deg.