Foundation™ Rooftop Units: Monthly Maintenance

Monthly Maintenance

Before completing the following checks, turn the unit OFF and lock the main power disconnect switch open.

! WARNING

Hazardous Voltage!

Failure to disconnect power before servicing could result in death or serious injury. Disconnect all electric power, including remote disconnects before servicing. Follow proper lockout/tagout procedures to ensure the power can not be inadvertently energized. Verify that no power is present with a voltmeter.

Filters

Inspect the return air filters. Clean or replace them if necessary. Refer to the unit Service Facts for filter information.

Condensate Overflow Switch

During maintenance, the switch float (black ring) must be checked to ensure free movement up and down.

With the unit running, check and record the following:

ambient temperature
compressor oil level (each circuit)
compressor suction and discharge pressures (each circuit)
superheat and subcooling (each circuit)

Record this data on an “operator’s maintenance log” like the one shown in Sample maintenance log table in Final Process Section. If the operating pressures indicate a refrigerant shortage, measure the system superheat and system subcooling. For guidelines, refer to “Compressor Start-Up,” p. 34.

Important: Do not release refrigerant to the atmosphere! If adding or removing refrigerant is required, the service technician must comply with all federal, state and local laws. Refer to general service bulletin MSCU-SB-1 (latest edition).

Heating Season

Inspect the unit’s air filters. If necessary, clean or replace them.
Check supply fan motor bearings; repair or replace the motor as necessary.
Inspect both the main unit control panel and heat section control box for loose electrical components and terminal connections, as well as damaged wire insulation. Make any necessary repairs.
Verify that the electric heat system operates properly.

Coil Cleaning

Regular coil maintenance, including annual cleaning enhances the unit’s operating efficiency by minimizing the following:

Monthly Maintenance

Before completing the following checks, turn the unit OFF and lock the main power disconnect switch open.

! WARNING

Hazardous Voltage!

Filters

Inspect the return air filters. Clean or replace them if necessary. Refer to the unit Service Facts for filter information.

Condensate Overflow Switch

During maintenance, the switch float (black ring) must be checked to ensure free movement up and down.

Cooling Season

Check the unit’s drain pans and condensate piping to ensure that there are no blockages.

Inspect the evaporator and condenser coils for dirt, bent fins, etc. If the coils appear dirty, clean them according to the instructions described in “Coil Cleaning” later in this section.

Manually rotate the condenser fans to ensure free movement and check motor bearings for wear. Verify that all of the fan mounting hardware is tight.

Inspect the F/A-R/A damper hinges and pins to ensure that all moving parts are securely mounted. Keep the blades clean as necessary.

Verify that all damper linkages move freely; lubricate with white grease, if necessary.

Check supply fan motor bearings; repair or replace the motor as necessary.

Check the fan shaft bearings for wear. Replace the bearings as necessary.

Check the supply fan belt(s). If the belts are frayed or worn, replace them. Refer to the “Fan Belt Adjustment-Belt Drive Units,” p. 36 for belt replacement and adjustments.

Verify that all wire terminal connections are tight.

Remove any corrosion present on the exterior surfaces of the unit and repaint these areas.

Generally inspect the unit for unusual conditions (e. g., loose access panels, leaking piping connections, etc.)

Make sure that all retaining screws are reinstalled in the unit access panels once these checks are complete.

With the unit running, check and record the following:

ambient temperature

compressor oil level (each circuit)

compressor suction and discharge pressures (each circuit)

superheat and subcooling (each circuit)

Important: Do not release refrigerant to the atmosphere! If adding or removing refrigerant is required, the service technician must comply with all federal, state and local laws. Refer to general service bulletin MSCU-SB-1 (latest edition).

Heating Season

Inspect the unit’s air filters. If necessary, clean or replace them.

Check supply fan motor bearings; repair or replace the motor as necessary.

Inspect both the main unit control panel and heat section control box for loose electrical components and terminal connections, as well as damaged wire insulation. Make any necessary repairs.

Verify that the electric heat system operates properly.

Coil Cleaning

Regular coil maintenance, including annual cleaning enhances the unit’s operating efficiency by minimizing the following:

Compressor head pressure and amperage draw

Evaporator water carryover

Fan brake horsepower

Static pressure losses

Airflow reduction