York Air Conditioner: H2CB

Re: High Head Pressure / Low Cooling

Especially during high ambient temperature conditions, the air conditioner exhibits the following conditions:

• High head pressure
• Hot liquid line
• Low cooling output

CHECKOUT:

1. Check Outdoor Fan

• Check the fan motor on the outdoor unit.
  • Many of these units require a "short-body" condenser fan motor.
    • If the condenser motor has been replaced with a standard motor, it may place the fan blade too low in the coil and cause high pressure issues.
• Set the thermostat to call for cooling.
• Inspect the outdoor unit and make sure the outdoor fan is operating.
  • Fan Operating --> Step 2. Check Pressures
  • No Fan --> Check Capacitor

2. Check Pressures

• Hook-up refrigerant gauges to the pressure ports on the unit.
• Blue --> Low Pressure (Big line)
• Red --> High Pressure (Small line)
• Monitor pressures as the system operates.

High Pressure Issues

• Place an insulated temperature probe on the liquid line near the outdoor unit.
• Allow the unit to run for at least 10 minutes.
• Monitor pressures and temperature as the system operates.
  • If pressure exceeds Normal Range or kicks-off on Hi Pressure safety in the first 5 minutes = Refrigerant Overcharge or No Condenser Fan
• Check Sub-Cooling
  • Record "Saturation Temperature" from the discharge pressure gauge.
  • Subtract the Actual liquid line temperature reading.
    • Sub-Cooling = Saturation Temp - Liquid Line Temp
      • Sub-Cooling > 13 deg. + High Discharge + High Suction = Refrigerant Overcharge
      • Sub-Cooling > 13 deg. + High Discharge + Low Suction = Bad Metering Device
      • Sub-Cooling < 2 deg. + High Discharge = Low Outdoor Heat Transfer --> Clean Condenser Coil & Recheck Sub-Cooling after 10 min.
        • Improved conditions = Dirty Condenser Coil
        • Same Conditions = Wrong Motor or Wrong Fan Blade