Carrier 69NT40-561-300, Operation And Service Manual

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T-365 7–22
7.18 ECONOMIZER EXPANSION VALVE
The economizer expansion valve is an automatic device that maintains constant superheat of the refrigerant gas
leaving at the point of bulb attachment, regardless of suction pressure.
Unless the valve is defective, it seldom requires maintenance other than periodic inspection to ensure that the ther-
mal bulb is tightly secured to the suction line and wrapped with insulating compound.
7.18.1 Economizer Expansion Replacement
Figure 7.17 Economizer Expansion Valve
1. Removing the Economizer Expansion Valve:
NOTICE
The economizer expansion valve is a hermetic valve, it does not have adjustable superheat (See
Figure 7.17 ).
a. Pump down the compressor (refer to Section 7.4 ) and frontseat both suction and discharge valves.
Evacuate if unit is not equipped with service valves. Refer to Section 7.6 .
b. Turn unit power off and remove power from the unit.
c. Remove cushion clamps located on the inlet and outlet lines.
d. Remove insulation (Presstite) from expansion valve bulb.
e. Unstrap the bulb, located on the economizer line.
f. VALVE REMOVAL: The preferred method of removing the valve is to cut the connection between the
brazed section and the valve, using a small tube cutter. Remove valve. Alternately, use a wet rag to keep
valve cool. Heat inlet and outlet connections to valve body and remove valve.
g. Clean the valve stem with mild cleaner, if necessary.
2. Installing the Economizer Expansion Valve:
a. The economizer expansion valve should be wrapped in a soaked cloth for brazing.
b. Braze inlet connection to inlet line.
c. Braze outlet connection to outlet line.
d. Reinstall the cushion clamps on inlet and outlet lines.
3. Replace filter drier, (Refer to Section 7.12 ).
4. Evacuate to 500 microns by placing vacuum pump on liquid line and suction service valve.
5. Check economizer expansion valve superheat (see Section 3.2 ).
Inlet
Outlet