Zamil MAC-240, Installation, Operation & Maintenance Manual

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9.8 REFRIGERANT CHARGING & PRESSURE LIMITS
If the air conditioning unit is to provide the proper amount of cooling, the refrigerant system needs to be adequately
charged with R-22 refrigerant. A shortage of refrigerant is evident by a loss of cooling effect, a low suction pressure, and
many bubbles present in the sight glass.
The necessity to add refrigerant is not considered routine maintenance. The loss of any portion of the refrigerant charge
indicates a refrigerant leak and thereby a need for service.
A liquid sight glass is located in the refrigerant piping just ahead of the expansion valve. When the refrigerant charge is
low, bubbles are evident in the liquid refrigerant flowing through the sight glass. Add refrigerant until the bubbles are
eliminated or only an occasional bubble is noticed.
WARNING:
DO NOT OVERCHARGE THE REFRIGERANT SYSTEM. OVERCHARGING THE SYSTEM CAN DAMAGE THIS
UNIT. THE ORIGINAL REFRIGERANT CHARGE FOR THIS UNIT IS LISTED BELOW.
A. REFRIGERANT CHARGE QUANTITY
Model MAC240 Air Conditioner Unit:
System-1 charge-R22: 450 oz (12.75 kg)
System-2 charge-R22:450 oz (12.75kg)
If the system has lost its charge completely, evacuate prior to recharging. Use the following procedure to add or replace
the refrigerant.
(1) Using a platform scale, weigh the R-22 Freon cylinder and its contents. Record this weight for later reference.
(2) Using a copper connecting tube or other appropriate charging hose, loosely connect the outlet of the Freon cylinder
to the charging valve.
(3) Position the R-22 Freon cylinder so that the top is at a higher level than the bottom. This is necessary to ensure the
release of the refrigerant in the gaseous state.
(4) Slightly open the valve on the R-22 Freon cylinder.
(5) Purge the charging line and tighten the connection.
(6) Check the tubing connections between the R-22 Freon cylinder and the charging valve for leaks.
(7) Open the valve on the Freon cylinder approximately halfway.
(8) Open the charging valve.
(9) Close the refrigerant valve on the liquid line to the expansion valve. Be sure the compressor suction and discharge
valves are open.
(10) Tip the R-22 Freon cylinder so that the outlet valve is at the lowest point allowing liquid refrigerant to flow through the
charging hose.
(11) Operate the compressor. The tubing connecting the R-22 Freon cylinder to the charging valve is not of sufficient
size to supply enough refrigerant to prevent the system from pumping down into a vacuum. Watch the suction
gauge and do not allow suction pressure to go below zero. The ideal pumping is to approach a vacuum without
actually pumping into a vacuum.
(12) If the system has lost its charge completely, charge only the specified weight of refrigerant into the system. DO NOT OVER-
CHARGE. Check that the refrigerant charge is free from bubbles and completely fills the sight glass.
(13) If the system has a partial charge, charge the system with only 10 pounds of R-22 Freon at a time. Stop the
charging operation and operate the unit in cool mode. Observe the refrigerant charge in the sight glass as stated
above. Repeat the procedure until the correct refrigerant charge is obtained without overcharging.
Compressor Oil
NOTE:
The compressors are sealed and do not require oil servicing.
B. REFRIGERANT PRESSURE SWITCH LIMITS
The refrigerant pressure switches are set properly to control the unit within the design parameters and are not adjustable.
If any refrigerant pressure switch fails to operate, replace the switch. The refrigerant pressure switch limits settings
are as follows:
High Pressure Switch (HPS) - 450 psig
Low Pressure Switch (LPS) - Cut-Out 25 psig, Cut-In 50 psig