TM9-4120-400-14
Section IV UNIT PREVENTIVE MAINTENANCE CHECKS AND SERVICES (PMCS)
4-6. GENERAL.
Systematic, periodic, preventive maintenance checks and services (PMCS) are essential to insure that the air
conditioner is ready for operation in any mode at all times. The purpose of a preventive maintenance program is to
discover and correct defects and deficiencies before they can cause serious damage or complete failure of the
equipment. Any effective preventive maintenance program must begin with the training of operators to report all
unusual conditions noted during daily checks or actual operation, to unit maintenance. All defects and
deficiencies discovered during maintenance inspections must be recorded, together with corrective action taken,
on DA Form 2404 (Equipment Inspection and Maintenance Worksheet).
a. A schedule for unit preventive maintenance inspection and service should be established immediately
after installation of the air conditioner. A quarterly interval, equal to three calendar months or 250 hours of
operation, whichever occurs first, is recommended for usual operating conditions. When operating under
unusual conditions, such as a very dusty or sandy environment, it may be necessary to reduce the interval
to monthly or even less if conditions are extreme.
b. Table 4-1 lists the unit preventive maintenance checks and services that should be performed at quarterly
(or otherwise established) intervals. The PMCS items in the table have been arranged and numbered in a
logical sequence to provide for greater personnel efficiency and least amount of required maintenance
downtime. The "Para Ref" (Paragraph Reference) column on the right side of the table provides the
paragraph number where detailed, step-by-step disassembly/reassembly maintenance procedures may
be found. The item number column will be used as a source of item numbers for the TM Number Column
on DA Form 2404.
Disconnect input power before disassembly of the air conditioner for PMCS to prevent
dangerous, possibly fatal, electrical shock.
