Maytag MFI2266AES Service Manual - Page 5

Component Testing ! 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 resistor before attempting to service. Ensure all ground wires are connected before certifying unit as repaired and/or operational. Component Compressor Description Test Procedures When compressor electrical circuit is Resistance test energized, the start winding current 1. Disconnect power to unit. causes relay to heat. After an amount of 2. Discharge capacitor by shorting across terminals with a resistor for 1 minute. starting time, the start winding circuit NOTE: (Some compressors do not have a run capacitor.) turns off. The relay will switch off the start 3. Remove leads from compressor terminals. winding circuit even though compressor 4. Set ohmmeter to lowest scale. has not started (for example, when 5. Check for resistance between attempting to restart after momentary Terminals "S" and "C", start winding power interruption). Terminals "R" and "C", run winding If either compressor winding reads open (infinite or very high resistance) or With "open" relay, compressor will not dead short (0 ohms), replace compressor. start because there is little or no current Ground test to start windings. Overload protection will 1. Disconnect power to refrigerator. open due to high locked rotor run winding 2. Discharge capacitor, if present, by shorting terminals through a resistor. current. 3. Remove compressor leads and use an ohmmeter set on highest scale. With "shorted" relay or capacitor, compressor will start and overload protector will quickly open due to high current of combined run and start windings. 4. Touch one lead to compressor body (clean point of contact) and other probe to each compressor terminal. • If reading is obtained, compressor is grounded and must be replaced. Operation test If voltage, capacitor, overload, and motor winding tests do not show cause for failure, perform the following test: With open or weak capacitor, compressor 1. Disconnect power to refrigerator. will start and run as normal but will 2. Discharge capacitor by shorting capacitor terminals through a resistor. consume more energy. 3. Remove leads from compressor terminals. 4. Wire a test cord to power switch. 5. Place time delayed fuse with UL rating equal to amp rating of motor in test cord socket. (Refer to Technical Data Sheet) 6. Remove overload and relay. 7. Connect start, common and run leads of test cord on appropriate terminals of compressor. 8. Attach capacitor leads of test cord together. If capacitor is used, attach capacitor lead to a known good capacitor of same capacity. To AC supply Switch Fuses Compressor CS R Capacitor Test configuration 9. Plug test cord into multimeter to determine start and run wattage and to check for low voltage, which can also be a source of trouble indications. 10. With power to multimeter, press start cord switch and release. • If compressor motor starts and draws normal wattage, compressor is okay and trouble is in capacitor, relay/overload, freezer temperature control, or elsewhere in system. • If compressor does not start when direct wired, recover refrigerant at high side. After refrigerant is recovered, repeat compressor direct wire test. If compressor runs after recovery but would not run when direct wired before recover, a restriction in sealed system is indicated. • If compressor does not run when wired direct after recovery, replace faulty compressor. ©2006 Maytag Services 16026312 5