IOMM AGZ-3 AGZ 035A through 065A 89
the sightglass could also indicate an excessive pressure drop in the liquid line, possibly due to a
clogged filter-drier or a restriction elsewhere in the liquid line. See Table 53 for maximum allowable
pressure drops). If subcooling is low add charge to clear the sightglass. If subcooling is normal (10°-
15°F) and flashing is visible in the sightglass check the pressure drop across the filter-drier.
Subcooling should be checked at full load with 70°F (21.1°C) outdoor air temperature and all fans
running.
An element inside the sightglass indicates the moisture condition corresponding to a given element
color. If the sightglass does not indicate a dry condition after about 12 hours of operation, the circuit
should be pumped down and the filter-drier changed.
Preventive Maintenance Schedule
PREVENTIVE MAINTENANCE SCHEDULE
OPERATION WEEKLY
MONTHLY
(Note 1)
ANNUAL
(Note 2)
General
Complete unit log and review (Note 3) X
Visually inspect unit for loose or damaged components X
Inspect thermal insulation for integrity X
Clean and paint as required X
Electrical
Check terminals for tightness, tighten as necessary X
Clean control panel interior X
Visually inspect components for signs of overheating X
Verify compressor heater operation X
Test and calibrate equipment protection and operating controls X
Megger compressor motor every five years *
Refrigeration
Leak test X
Check sight glasses for clear flow X
Check filter-drier pressure drop (see manual for spec) X
Perform compressor vibration test X
Condenser (air-cooled)
Clean condenser coils (Note 4) X
Check fan blades for tightness on shaft (Note 5) X
Check fans for loose rivets and cracks X
Check coil fins for damage X
Notes:
1. Monthly operations include all weekly operations.
2. Annual (or spring start-up) operations includes all weekly and monthly operations.
3. Log readings can be taken daily for a higher level of unit observation.
4. Coil cleaning can be required more frequently in areas with a high level of airborne particles.
5.
Be sure fan motors are electrically locked out.
* Never Megger motors while they are in a vacuum.
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