Hoshizaki F-800MAF, Service Manual

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5. REMOVAL AND REPLACEMENT OF EXPANSION VALVE
IMPORTANT
Sometimes moisture in the refrigerant circuit exceeds the Drier capacity and
freezes up at the Expansion Valve. Always install a new Drier every time the
sealed refrigeration system is opened. Do not replace the Drier until after all
other repairs or replacement have been made.
1) Turn off the power supply, and remove the panels.
2) Recover the refrigerant and store it in an approved container, if required by an applicable
law.
3) Remove the Expansion Valve Bulb at the Evaporator outlet.
4) Remove the Expansion Valve Cover, and remove the Expansion Valve using brazing
equipment.
5) Braze the new Expansion Valve with nitrogen gas flowing at the pressure of 3 - 4 PSIG.
WARNING
Always protect the valve body by using a damp cloth to prevent the valve from
overheating. Do not braze with the valve body exceeding 250°F.
6) Install the new Drier.
7) Check for leaks using nitrogen gas (140 PSIG) and soap bubbles.
8) Evacuate the system. Charge it with refrigerant. For the air-cooled and water-cooled
models, see the Nameplate for the required refrigerant charge and type. For the remote
air-cooled models, see the label on the Control Box.
9) Attach the Bulb to the suction line. Be sure to secure the Bulb using a band and to
insulate it.
10) Place the new set of Expansion Valve Covers in position.
11) Replace the panels in their correct position, and turn on the power supply.