Carrier 69NT40-561-019, Operation And Service Manual

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7–17 T-359
Figure 7.9 Electronic Expansion Valve
7.12.1 Replacing Electronic Expansion Valve and Strainer
a. Removing an EEV:
1. Pump down compressor (refer to Section 7.3.2 ) and frontseat both suction and discharge valves.
2. Turn unit power off and remove power from the unit.
3. Remove coil.
4. 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 and the strainer.
5. Alternately, use a wet rag to keep valve cool. Heat inlet and outlet connections to valve body and
remove valve.
6. Clean the valve stem with mild cleaner, if necessary.
b. Installing an EEV, reverse steps 1 through 4 above to install a new valve:
1. Install the valve and a new strainer with the cone of strainer / screen pointing into liquid line at the inlet to
the valve.
2. During installation, make sure the EEV coil is snapped down fully, and the coil retention tab is properly
seated in one of the valve body dimples. Also, ensure that coil boot is properly fitted over valve body.
See
Figure 7.9 .
3. Replace filter drier.
4. Evacuate to 500 microns by placing vacuum pump on liquid line and suction service valve.
5. Open liquid line service valve and check refrigerant level.
6. Check superheat. (Refer to Section 3.2 ).
7. Check unit operation by running Pre-trip (Refer to Section 4.6 ).
7.13 ECONOMIZER EXPANSION VALVE
The economizer expansion valve can be found in Figure 3.4 (Item12). The economizer expansion valve is an auto-
matic 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.
FLOW
DIRECTION
1. Coil Boot
2. Coil
3. Electronic
Expansion Valve
4. Strainer