PREVOST H3-41 Maintenance Manual page 876

SECTION 22: HEATING AND AIR CONDITIONING
4.7.1 Replacement Of The Filter-Dryer After Pumping Down ....................................................................... 35
4.8 MOISTURE INDICATOR ................................................................................................................................. 35
4.9 SHUT-OFF VALVE WITH SERVICE PORT ........................................................................................................ 37
4.10 LIQUID REFRIGERANT SOLENOID VALVE...................................................................................................... 37
4.10.1 Typical Malfunctions ............................................................................................................................ 37
4.10.2 Electrical Bypass/On Demand Opening Of Liquid Refrigerant Solenoid Valves ................................... 38
4.10.3 Coil Replacement ................................................................................................................................. 38
4.10.4 Valve Disassembly ................................................................................................................................ 38
4.10.5 Valve Reassembly ................................................................................................................................ 38
4.11 THERMOSTATIC EXPANSION VALVE ............................................................................................................ 39
4.11.1 Central System ..................................................................................................................................... 39
4.11.2 Superheat Adjustment ......................................................................................................................... 40
4.11.3 Maintenance ........................................................................................................................................ 41
4.11.4 Driver's Unit ......................................................................................................................................... 41
4.12 HOT WATER PNEUMATIC VALVE ................................................................................................................. 42
4.12.1 Valve Troubleshooting ......................................................................................................................... 43
4.13 HOT WATER CIRCULATING PUMP ................................................................................................................ 43
4.13.1 Central HVAC System ........................................................................................................................... 43
4.13.2 Small HVAC System .............................................................................................................................. 44
4.13.3 Removal ............................................................................................................................................... 44
4.13.4 Installation ........................................................................................................................................... 44
5. HVAC SYSTEM TESTING AND TROUBLESHOOTING........................................................................................ 45
5.1 ON DEMAND DISPLAY OF A/C SYSTEM HIGH AND LOW SIDE PRESSURE .................................................... 45
5.2 ON DEMAND ACTIVATION OF HOT WATER CIRCULATING PUMP ............................................................... 45
5.3 TEMPERATURE SENSORS ............................................................................................................................. 45
5.4 TEST MODE FOR SWITCHES AND SENSORS ................................................................................................. 46
5.5 TEST MODE FOR ELECTRIC MOTORS ........................................................................................................... 47
5.6 MODES OF OPERATION ............................................................................................................................... 47
5.7 HVAC ELECTRICAL SYSTEM TROUBLESHOOTING ......................................................................................... 48
5.7.1 Air Conditioning ................................................................................................................................... 50
5.7.2 Expansion Valve ................................................................................................................................... 52
5.8 TEMPERATURES & PRESSURES CHART ........................................................................................................ 53
5.9 LEAK TESTING............................................................................................................................................... 53
6. CENTRAL HVAC SYSTEM ............................................................................................................................... 53
6.1 AIR CIRCULATION IN DRIVER'S AREA ........................................................................................................... 54
6.2 AIR CIRCULATION IN PASSENGER'S AREA .................................................................................................... 55
6.3 HVAC SYSTEM OPERATION .......................................................................................................................... 56
6.3.1 Control Unit .......................................................................................................................................... 56
6.3.2 Overhead Compartment Unit .............................................................................................................. 57
6.4 HEATING ...................................................................................................................................................... 57
6.4.1 Driver's Unit Hot Water Pneumatic Valve ............................................................................................ 57
6.4.2 Passenger's Unit Hot Water Pneumatic Valve ..................................................................................... 57
6.4.3 Draining Heating System ..................................................................................................................... 57
6.4.4 Filling Heating System .......................................................................................................................... 60
6.4.5 Bleeding Heating System ..................................................................................................................... 61
6.5 COOLING ...................................................................................................................................................... 61
6.5.1 Refrigeration Cycle ............................................................................................................................... 61
6.5.2 Refrigerant ........................................................................................................................................... 61
6.5.3 Refrigerant System Clean-Out After Compressor Failure ..................................................................... 63
6.5.4 Pumping Down ..................................................................................................................................... 64
6.5.5 Adding Vapor State Refrigerant ........................................................................................................... 66
2 PA1621 Maintenance Manual All Series | Revised February 2019