Maytag MFI2266AES Service Manual - Page 17

Service Procedures ! WARNING To avoid risk of electrical shock, personal injury, or death, disconnect electrical power source to unit, unless test procedures require power to be connected. Discharge capacitor through a 10,000 ohm resistor before attempting to service. Ensure all ground wires are connected before certifying unit as repaired and/or operational. Replacement Service Compressor HFC134a service compressors will be charged with ester oil and pressurized with dry nitrogen. Before replacement compressor is installed, pull out 1 rubber plug. A pop from pressure release should be heard. If a pop sound is not heard, do not use compressor. Positive pressure in compressor is vital to keep moisture out of ester oil. Do not leave compressor open to atmosphere for more than 10 minutes. Compressor Testing Procedures ! WARNING To avoid death or severe personal injury, never use oxygen, air or acetylene for pressure testing or clean out of refrigeration system. Use of oxygen, air, or acetylene may result in violent explosion. Oxygen may explode on contact with oil and acetylene will spontaneously explode when under pressure. Refer to Technical Data Sheet "Temperature Relationship Chart" for operating watts, test points, and temperature relationship test for unit being tested. • Temperature testing is accomplished by using 3 lead thermocouple temperature tester in specific locations. Test point T-1 is outlet on evaporator coil and T-2 is inlet. Test point T-3 is suction tube temperature midway between where armaflex ends and suction port of compressor (approximately 12 inches from compressor). • Thermocouple tips should be attached securely to specified locations. • Do not test during initial pull down. Allow one off cycle or balanced temperature condition to occur before proceeding with testing. • Refrigerator must operate minimum of 20 minutes after thermocouples are installed. • Turn control to colder to obtain required on time. • Wattage reading must be recorded in conjunction with temperature test to confirm proper operation. • Suction and head pressures are listed on "Temperature and Relationship Chart". Normally these are not required for diagnosis but used for confirmation on systems which have been opened. Brazing ! CAUTION To avoid risk of personal injury or property damage, take necessary precautions against high temperatures required for brazing. Satisfactory results require cleanliness, experience, and use of proper materials and equipment. Connections to be brazed must be properly sized, free of rough edges, and clean. Generally accepted brazing materials are: • Copper to copper joints: SIL-FOS (alloy of 15 percent silver, 80 percent copper, and 5 percent phosphorous). Use without flux. Recommended brazing temperature is approximately 1400°F. Do not use for copper to steel connection. • Copper to steel joints: SILVER SOLDER (alloy of 30 percent silver, 38 percent copper, 32 percent zinc). Use with fluoride based flux. Recommended brazing temperature is approximately 1200°F. • Steel to steel joints: SILVER SOLDER (see copper to steel joints). • Brass to copper joints: SILVER SOLDER (see copper to steel joints). • Brass to steel joints: SILVER SOLDER (see copper to steel joints). ©2006 Maytag Services 16026312 17