Chapter 4. OPERATOR MAINTENANCE INSTRUCTIONS FOR AUXILIARY EQUIPMENT

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TM-55-1905-219-14-9 Landing Craft Utility (LCU) 1667 Class Boston Hull Numbers 1667-1670 NSN 1905-00-168-5764 Manual

THERMAL EXPANSION VALVE - AIR CONDITIONING - MAINTENANCE INSTRUCTIONS

TM 55-1905-219-14-9

CHAPTER 4

OPERATOR MAINTENANCE INSTRUCTIONS FOR

AUXILIARY EQUIPMENT (CONTINUED)

SECTION IV. TROUBLESHOOTING - SYMPTOM INDEX (con't)

4-34. THERMAL EXPANSION VALVE - AIR CONDITIONING - MAINTENANCE INSTRUCTIONS.

General.

(1) Thermal expansion valve troubles can usually be traced to dirt or moisture collecting at the valve seat

and orifice. Dirt will get between the valve seat and stem, or moisture will freeze at the valve port, and prevent

the passage of refrigerant. External frost on the inlet side of the valve indicates an obstruction and the need for

cleaning.

(2) To clean, inspect, or repair a thermal expansion valve, pump down the strainer and controls as

explained in paragraph b and disassemble the valve.

(3) A new power or cage assembly, or both, can be installed without removing the valve body flange from

the line.

NOTE

In an emergency, expansion valve freeze up may be avoided by adding to system not more

than 1 cc of anhydrous methyl alcohol per pound of refrigerant charge.

Pumping Down.

To replace the thermal expansion valve, proceed as follows:

(1)

Close the cut-out valve on the inlet side of the strainer, and operate system to pump down.

(2)

As the pressure is reduced, the strainer will become cold and then begin to warm up as soon as liquid

refrigerant has been removed.

(3)

Close the cut-out valve on the outlet side.

(4)

Disassemble valve.

(5) Remove thermal expansion valve in accordance with standard soldering methods. Be careful to retain

all the solder in the connections. Refer to paragraph 4-35.6 for soldering procedures.

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