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

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T-365 7–20
7.16 ELECTRONIC EXPANSION VALVE
The electronic expansion valve (EEV) is an automatic device which maintains required superheat of the refrigerant
gas leaving the evaporator. The valve functions are: (a) automatic response of refrigerant flow to match the evapo-
rator load and (b) prevention of liquid refrigerant entering the compressor. Unless the valve is defective, it seldom
requires any maintenance.
7.16.1 Replacing Electronic Expansion Valve and Strainer
Removing an EEV:
WARNING
!
Always turn OFF the unit circuit breakers (CB-1 & CB-2) and disconnect main power supply
before working on moving parts.
1. Pump down the compressor (refer to Section 7.4 ) 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.
Alternately, use a wet rag to keep valve cool. Heat inlet and outlet connections to valve body and remove
valve.
5. Clean the valve stem with mild cleaner, if necessary.
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 7.15 .
Figure 7.15 Electronic Expansion Valve
3. Replace filter drier.
4. Evacuate to 500 microns by placing vacuum pump on liquid line and suction service valve.
FLOW
DIRECTION
Coil
Boot
Coil
Electronic
Expansion
Valve
Strainer