Truck/Trailer Refrigeration Unit - Sunbelt Transport Refrigeration

4.10 CHARGING THE REFRIGERATION SYSTEMCAUTIONDo not vapor charge R-404A. Only liquidcharging through the liquid line king valve isacceptable.a. Dehydrate unit and leave in deep vacuum. (Refer tosection 4.9)b. Place refrigerant cylinder on scale and connectcharging line from cylinder to receiver outlet (king) valve.Purge charging line at outlet valve.c. Note weight of refrigerant cylinder.d. Open liquid valve on refrigerant cylinder. Open kingvalve half way and allow the liquid refrigerant to flow intothe unit until the correct weight of refrigerant has beenadded as indicated by scales. Correct charge will be foundin Section 1.3.NOTEIt is possible that all liquid may not be pulled intothe receiver, as outlined in step (d). In this case,frontseat the receiver outlet valve (king valve)and the liquid will be pulled into the system. Unitmust be operating in the cooling mode.e. When refrigerant cylinder weight (scale) indicatesthat the correct charge has been added, close liquid linevalveoncylinderandbackseatthekingvalve.4.10.1 Checking the Refrigerant Chargea. Start unit in cooling mode. Run approximately tenminutes. Partially block off air flow to condenser coil sodischarge pressure rises to 14.8 kg/cm@ (210 psig).The unit is correctly charged when the middlereceiver sight glass is full and no refrigerant is in theupper receiver sight glass.4.11 REPLACING THE COMPRESSOR (TRUCK)a. RemovingIf compressor is inoperative and unit still hasrefrigerant pressure, frontseat suction and dischargeservice valves to trap most of the refrigerant in the unit.If compressor runs, pump down the unit. (Refer toSection 4.7.a)1. Slowly release compressor pressure to a recoverysystem.2. Remove bolts from suction and discharge servicevalve flanges.3. Disconnect wiring to compressor dischargetemperature sensor (CDT), suction pressure transducerand the wiring to the high pressure switch (HP).4. Release idler pulleys and remove belts.5. Remove the four bolts holding the compressor tothe power tray. Remove the compressor from chassis.6. Remove the pulley from the compressor.7. Drain oil from defective compressor beforeshipping.b. Installing1. To install the compressor, reverse the procedureoutlined when removing the compressor. Refer toSection 4.28 for torque values.NOTEThe service replacement compressor is soldwithout shutoff valves (but with valve pads).Customer should retain the original capacitycontrol valves for use on replacementcompressor. Check oil level in servicereplacement compressor. (Refer to Sections 1.3,and 4.13.)2. Attach two lines (with hand valves near vacuumpump) to the suction and discharge service valves.Dehydrate and evacuate compressor to 500 microns(29.90” Hg vacuum = 75.9 cm Hg vacuum). Turn offvalves on both lines to pump.3. Fully backseat (open) both suction and dischargeservice valves.4. Remove vacuum pump lines and install manifoldgauges.5. Check refrigerant level (Refer to section 4.10.1.)NOTEIt is important to check the compressor oil levelof the new compressor and fill if necessary.6. Check compressor oil level. (Refer to Section4.13.) Add oil if necessary.7. Check refrigerant cycles.4.12 REPLACING THE COMPRESSOR (TRAILER)If compressor is inoperative and unit still hasrefrigerant pressure, frontseat suction and dischargeservice valves to trap most of the refrigerant in the unit.If compressor runs, pump down the unit. (Refer toSection 4.7.a.)a. Remove the two rear compressor bracket mountingbolts (compressor shockmount end).b. Block up engine.c. Slowly release compressor pressure to a recoverysystem.d. Remove bolts from suction and discharge servicevalve flanges.e. Remove oil filter and bracket from 05G compressor.f. Disconnect wiring to unloader valve assemblies,compressor discharge temperature sensor (CDT),suction pressure transducer and the wiring to the highpressure cutout switch (HP-1).g. Remove 10 bolts from the engine-compressor spacer.h. Disconnect ground strap from frame.i. Disconnect suction pressure transducer fromcompressor .j. Attach sling or other device to the compressor.4-13 62-02884