Operating instructions

IMM AGSB-60 61
Service
CAUTION
1. Service on this equipment is to be performed by qualified refrigeration
personnel familiar with equipment operation, maintenance, correct servicing
procedures, and the safety hazards inherent in this work. Causes for
repeated tripping of equipment protection controls must be investigated and
corrected.
2. Anyone servicing this equipment must comply with the requirements set
forth by the EPA regarding refrigerant reclamation and venting.
DANGER
Disconnect all power before doing any service inside the unit to avoid bodily
injury or death. Multiple power sources can feed the unit.
Liquid Line Filter-Driers
A replacement of the filter-drier cores is recommended any time excessive pressure drop is
read across the filter-drier and/or when bubbles occur in the sight glass with normal
subcooling. There are two two-core driers in each circuit. The maximum recommended
pressure drop across the filter-drier is as follows:
Table 31, Liquid Line Filter-Drier Pressure Drop
Percent Circuit
Loading (%)
Maximum Recommended Pressure
Drop Across Filter Drier psig (kPa)
100%
7 (48.3)
75% 5 (34.5)
50% 3 (20.7)
25% 3 (20.7)
Change the filter-driers when the moisture indicating liquid line sight glass indicates excess
moisture in the system, or an oil test indicates the presence of acid.
During the first few months of operation, filter-drier replacement can be necessary if the
pressure drop across the filter-drier exceeds the values listed in the table above. Any residual
particles from the condenser tubing, compressor and miscellaneous components are swept by
the refrigerant into the liquid line and are caught by the filter-drier.
The following is the procedure for changing the filter-drier core:
The standard unit pumpdown is set to stop pumpdown when 25 psig (172 kPa) suction
pressure is reached. To fully pump down a circuit beyond 25 psig (172 kPa) for service
purposes, a "Full Pumpdown" service mode can be activated on the circuit controller using the
keypad.
With Full Pumpdown = Yes, then the next time the circuit is pumped down, the pumpdown
will continue until the evaporator pressure reaches 15 psig (103 kPa) or 120 seconds have
elapsed, whichever occurs first. Upon completing the pumpdown, the "FullPumpDwn"
setpoint is automatically changed back to "No".
The procedure to perform a full service pumpdown for changing the filter-drier core is as
follows: