York Rooftop Unit ZH078E54D5B5BCA2A1

Review the installation for any errors, leaks, or undesirable system effects.

Ensure only qualified personnel make blower speed changes.

Enter the measured CFM at unit start-up.

Enter the existing datum diameter (DD) of the motor sheave.

Calculate and enter the new datum diameter (DD) using the formula: Required CFM / Measured CFM × Existing DD.

Is the unit equipped with power exhaust fans or a return air fan?

Belt Tension Adjustment Procedure

Loosen the four bolts holding the motor base to the channels

Adjust the belt by turning nuts 'A' (see detail 'B')

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

Enter the deflection distance obtained (in inches)

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

Use the recommended deflection force per the Belt Adjustment Table

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 functionality

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

Determine the pressure drop across a dry evaporator coil using an Inclined Manometer or Magnehelic

Are the compressors de-energized before taking measurements?

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 the electrical supply voltage being supplied

Is the electrical supply voltage the same as listed on the unit nameplate?

Set the room thermostat to the off position

Set the room thermostat fan switch to on

Is the indoor blower rotation correct?

Check blower drive belt tension

Check the unit supply air (CFM)