Lennox MPA009S4S Service Manual page 4

19.4. Outdoor Unit Digital Display Tube ............................................................................................................................... 93
19.5. Dry Mode Operation - MWMA and MWMB ................................................................................................................. 93
19.6. Test Run - MWDA and MWMB .................................................................................................................................... 93
19.7. Double-Check Pipe Connections ................................................................................................................................ 94
19.8. Ambient Temperature is Below 63°F (17°C) ............................................................................................................... 94
20. Quick Reference Guide - Error Codes ................................................................................. 95
21. Single-Zone Outdoor Unit LED Locations ........................................................................... 97
22. Multi-Zone Outdoor Unit LEDs and SW1 Locations ......................................................... 101
23. Troubleshooting Outdoor Unit Error Codes ...................................................................... 102
24. Indoor Unit Indicators and Controls .................................................................................. 126
24.1. Cassette Unit Display ................................................................................................................................................ 126
24.2. Ducted Unit Display................................................................................................................................................... 126
24.3. Wall-Mounted and Ceiling/Floor Unit Displays .......................................................................................................... 127
25. Troubleshooting Indoor Unit Error Codes ......................................................................... 128
26. Temperature Sensor Resistance Values ............................................................................ 152
27. Discharge Temperature Sensor Resistance Values ......................................................... 153
28. Temperature Sensor Identification Table........................................................................... 154
29. Component Troubleshooting .............................................................................................. 154
29.1. Compressor Check ................................................................................................................................................... 154
29.2. IPM Check ................................................................................................................................................................. 155
29.3. AC Fan Motor ............................................................................................................................................................ 156
29.4. Four-Way Valve ......................................................................................................................................................... 157
29.5. EXV Check ................................................................................................................................................................ 158
30. Component Protection ........................................................................................................ 159
30.1. Fan Motor .................................................................................................................................................................. 159
30.2. Inverter Module Protection ........................................................................................................................................ 159
30.3. Low Voltage Protection ............................................................................................................................................. 159
30.4. Compressor Current Limit Protection ........................................................................................................................ 159
31. Specifications and Operations ........................................................................................... 160
31.1. Capacity Request Calculations ................................................................................................................................. 161
31.2. Defrost Control .......................................................................................................................................................... 163
31.3. Defrost Theory .......................................................................................................................................................... 163
31.4. Defrost Termination ................................................................................................................................................... 164
31.5. Outdoor Fan Control ................................................................................................................................................. 164
31.6. Four-Way Valve Control ............................................................................................................................................ 165
31.7. Electronic Expansion Valve (EXV) Control ................................................................................................................ 166
32. Index ..................................................................................................................................... 167
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