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.
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.
Due to the soft material and thin walls of the MCHE coils, the traditional field maintenance method recommended for Round Tube Plate Fin (RTPF) coils does not apply to microchannel coils. Moreover, chemical cleaners are a risk factor to MCHE due to the material of the coil. The manufacturer does not recommend the use of chemical cleaners to clean microchannel coils. Using chemical cleaners could lead to warranty claims being further evaluated for validity and failure analysis
Source: MaintainX (Community Member)