Before completing the following checks, turn the unit OFF and lock the main power disconnect switch open.
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.
Inspect the return air filters. Clean or replace them if necessary. Refer to the unit Service Facts for filter information.
Return Air Smoke Detector Maintenance
Airflow through the unit is affected by the amount of dirt and debris accumulated on the indoor coil and filters.
To insure that airflow through the unit is adequate for proper sampling by the return air smoke detector, complete adherence to the maintenance procedures, including recommended intervals between filter changes, and coil cleaning is required.
For detailed instructions concerning these checks and procedures, refer to the appropriate section(s) of the smoke detector Installation and Maintenance Instructions provided with the literature package for this unit.
Periodic checks and maintenance procedures must be performed on the smoke detector to insure that it will function properly
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:
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).
Regular coil maintenance, including annual cleaning enhances the unit’s operating efficiency by minimizing the following:
Microchannel (MCHE) Coils
Failure to follow instructions below could result in coil damage. DO NOT use any detergents with microchannel condenser coils. Use pressurized water or air ONLY, with pressure no greater than 600psi.
The recommended cleaning method for microchannel condenser coils is pressurized water or air with a nonpinpoint nozzle and an ECU of at least 180 with pressure no greater than 600 psi. To minimize the risk of coil damage, approach the cleaning of the coil with the pressure washer aimed perpendicular to the face of the coil during cleaning.
Round Tube Plate Fin (RTPF) Coils
To clean refrigerant coils, use a soft brush and a sprayer (either a garden pump-up type or a high-pressure sprayer). A high-quality detergent is also required; suggested brands include “SPREX A.C.”, “OAKITE 161”, “OAKITE 166” and “COILOX”. If the detergent selected is strongly alkaline (ph value exceeds 8.5), add an inhibitor.
Failure to follow all safety instructions below could result in death or serious injury. Coil cleaning agents can be either acidic or highly alkaline and can burn severely if contact with skin occurs. Handle chemical carefully and avoid contact with skin. ALWAYS wear Personal Protective Equipment (PPE) including goggles or face shield, chemical resistant gloves, boots, apron or suit as required. For personal safety refer to the cleaning agent manufacturer’s Materials Safety Data Sheet and follow all recomme
Safe Handling Practices:
Source: MaintainX (Community Member)