York Rooftop Unit ZH090E54D5B5BCA2A1

Check the electrical supply voltage being supplied

Set the room thermostat to the off position

Set the room thermostat fan switch to on

Check blower drive belt tension

Check the unit supply air (CFM)

Measure evaporator fan motor's amp draw

Ensure power to the smoke detector is turned off

Inspect the smoke detector for any visible damage

Remove the smoke detector cover

Clean the smoke detector using a soft brush or vacuum cleaner

Reattach the smoke detector cover

Test the smoke detector to ensure it is functioning properly

Remove the dot plugs from the duct panel

Insert eight inches of 1/4 inch metal tubing into the airflow on both sides of the indoor coil

Ensure tubes are perpendicular to the airflow to avoid velocity pressure affecting static pressure readings

Use an Inclined Manometer or Magnehelic to determine the pressure drop across a dry evaporator coil

Are the compressors de-activated to assure a dry coil?

Determine the CFM through the unit from the pressure drop indicated by the manometer

Adjust Measured CFM to Required CFM, see SUPPLY AIR DRIVE ADJUSTMENT

Check if the unit is equipped with additional fans

Belt Tension Adjustment Procedure

Loosen the four bolts holding the motor base to the channels

Adjust the belt by turning nuts 'A'

Apply perpendicular force to one belt at the midpoint of the span using a belt tension checker

Enter the deflection distance obtained

Use a straight edge from sheave to sheave as a reference line to determine deflection distance

Tension new belts at the maximum deflection force recommended

Review installation for errors, leaks, or undesirable system effects

Ensure only qualified personnel make blower speed changes

Blower Speed Change Considerations

Understand that small changes in blower speed can result in substantial changes in static pressure and BHP

Acknowledge that BHP and AMP draw will increase by the cube of the blower speed

Acknowledge that static pressure will increase by the square of the blower speed