4-14.1.5 Maintenance Allocation Chart (MAC) Is In TM 55-1930-209-14&P-18. For maintenance on other
onboard equipment, consult appropriate manual.
4-14.2 Maintenance instructions. Maintenance instructions are presented In the paragraphs that follow
paragraph 4-15, Preventive maintenance checks and services, paragraph 4-16, Troubleshooting; and paragraph
4-17, Maintenance procedures
4-15 Preventive maintenance checks and services. Refer to Chapter 3, TM 55-1930-209-14&P-19
4-16 Troubleshooting. Troubleshoot HAC system In accordance with Table 4-2
4-17 Maintenance procedures
4-17.1 Air conditioning unit. Maintenance procedures are provided in Chapter 6, Commercial Manual for 5 Ton
Marine Air Conditioner Model NAC-600 This manual is In Appendix B
4-17.2 Air filter replacement
Remove two screws on each side of center section of front grill. Lift up and set away from work area. Remove
Never use alkaline solutions or cleaning solvents to clean air filter. Fumes from such
substances may be harmful. In addition, they remove protective finish from filter surfaces.
Never operate AC unit without a filter. This allows foreign material to enter evaporator and fan
section, causing them to clog, thus reducing cooling capacity and ultimately damaging system.
Clean air filter by washing with fresh water under pressure Water should be forced through filter in opposite
direction from airflow to force dirt, lint, and foreign material out of and off of filter surfaces. If this does not clean
filter, soak In warm soapy water and then thoroughly rinse with water under pressure. When filter Is dry, coat
very lightly with an odorless lightweight lubricating oil. If filter shows signs of coming apart, replace with one
measuring 18 Inches by 36 Inches by 1 inch
Inspect and clean interior surfaces and equipment behind grill. Use brush to remove dust and lint from AC coils
Reinstall filter and center section of front grill. Make sure two screws on side of grill are tight.
4-17.3 Fan belt replacement
Remove top center section of front grill by removing two screws on sides of grill Lift up and out and set away
from work area
Check fan belt.
(1) If loose, adjust by loosening four screws holding fan motor in place. Pull motor forward until belt is tight,
hold In that position, and tighten four screws.
If a fan belt is frayed and worn on edges or has cracks penetrating at least 1/4 inch, replace belt Loosen
four screws holding fan motor In place and push motor back in compartment. Replace old fan belt with
new belt and pull motor forward until belt is firmly tight. Hold In that position and tighten four screws.
Do not lubricate bearings in AC unit fan and motor. They are lubricated for life by manufacturer.
Clean motor exterior and make sure air inlet and outlet are clean and free of foreign material.
Reinstall top center section of front grill. Make sure two screws on sides of grill are tight.