Left Side Discharge Pressure Regulator

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Left Side Discharge Pressure Regulator. Remove Cap to Adjust Valve Schrader Valve. Adjusting Discharge Pressure Regulating Valve. Unit must be on defrost for adjustment of setting Proper setting for R404a is ~ 240 to 270 psig Use 5/16 inch Allen wrench to adjust - PowerPoint PPT Presentation

Text of Left Side Discharge Pressure Regulator

  • Left Side Discharge Pressure RegulatorRemove Cap to Adjust Valve Schrader Valve

  • Adjusting Discharge Pressure Regulating ValveUnit must be on defrost for adjustment of setting Proper setting for R404a is ~ 240 to 270 psig Use 5/16 inch Allen wrench to adjust CW rotation increases pressure, CCW decreases pressure Replace cap after adjustment

  • Right Side Suction Pressure Regulator & Hot Gas Valve

    Electrical connection to Solenoid of Valve Hot Gas Valve Remove cap to adjust suction pressure regulator valve Electrical cable to compressor junction box

  • Adjusting Suction Pressure Regulating ValveBox temp should be above 5 CSetting should be ~ 30 to 35 psig for R404AUse 5/16 inch Allen wrench to adjust1 turn changes setting by 2.5 psigCW rotation increases pressure, CCW decreases pressureRun system 15 minutes to confirm settingBe sure to replace cap

  • Filter Dryer & sight glass with protective cover

    To replace Filter Dryer:Have new filter ready for installationPerform Low Side Pump down, but make sure to have a slight positive presureLoosen BracketLoosen flare nutsReplace filterTighten flare nutsTighten bracketOpen liquid line hand valve

  • Liquid Line Sight Glass & Filter DryerCheck for moisture in systemObserve color in sight glassIf yellow replace filter dryer and recycle the refrigerantRun for 12 hours or until sight glass is green, and look for leaks on the suction sideIf not green after 12 hours, replace filter dryer, recycle and look for leaks again

  • Hot Gas Solenoid Valve for DefrostSolenoid of the Hot Gas valve

    Hot Gas valve When energized directs hot gas to the evaporator for evaporator coil defrosting Suction pressure regulating valve

  • High Pressure SwitchesIf pressure too high switch opens and de-energizes compressor contactor coil Right side compressor high pressure safety switch Unscrew flare fitting to remove switch Left side compressor high pressure safety switch Loom removed to show switch wires

  • Compressor checkWith condenser contactor disconnected run unit Discharge pressure should increase until high pressure switch opens Close hand valve on receiver Compressor should pump down to 15 20 inches Vacuum or lower Check current on L1, L2 and L3; 7 to 12 Amps is OK

  • TXV Placement and AdjustmentTXV located in unitProper Bulb locationTightly clamped to suction lineAfter it is properly located and clamped, bulb is wrapped with insulation (not shown)Remember TXV is set at factory and should not need adjustment

  • Thermal Expansion Valve (TXV)Sensing Bulb Capillary line Power Element Liquid Line in Line out to Distributor Equalizer Line Removable Cap for adjustment

  • TVX Adjustment is Seldom RequiredPull container down to -20 CRemove cap from TX with adjustable wrenchAdjust superheat (SH) setting with refrigeration wrenchCCW reduces SH and CW increases SHDo not adjust more than 1 turnLet system run and settle outIt may take as much as 30 minutes for the system to balance after the adjustmentReplace cap

  • Detecting Blockage in Refrigeration SystemBlockage is usually caused by dirt, moisture, or TXV power element loosing its chargeBlockage can be detected by lower than normal suction pressure and reduced capacityWhen moisture in the system exceeds the capacity of the dryer to remove it, ice will form in the dryer. This causes a pressure drop and the liquid refrigerant will evaporate. There may be frost on the dryer and/or the liquid line leaving the dryer.There will not always be frost visible, but the liquid into the dryer should be warm and the liquid out should be coldDirt or moisture may cause the TXV to stick in one positionCheck this by watching the suction gauge to see if the TXV is modulating. It the suction pressure stays steady the TXV is stuck. The evaporator return air temp must be at -5 C or below to check this.Check for frozen TXVShut unit downWait ~ 20 minutes for ice on TXV to meltAt start up unit operation should be normal, after running for awhile if the TXV again sticks and does not modulate, then the problem is moisture.If after start up, unit operation has not changed it is most likely dirt in the system or the TXV element has lost its charge

  • Properly Adjusted TXV ConditionsSuction Line from Evaporator

    Should be frost on suction line Possible frost on suction service valve (not shown) Little or no frost on end of bell Oil sump should feel warm

  • Evaporator Coil with Temperature ProbesHot Gas Defrost Line

    Return Air temperature probe Defrost temperature probe

  • Condenser Section with Grill removedCondenser fan Motor junction box Coils

  • Evaporator Supply Air DischargeLouvers removed to show supply air port

    Evaporator fan pulls return air through evaporator coil And blows it through this opening into the cargo area Louvers prevent short cycling of supply air back into evaporator section

  • Left Side Right SideLiquid Receivers with Sight Glasses

  • Fusible Plug and Purge Valve of Receiver

    Purge Valve Fusible Plug Hand Valve Purge Valve from rear Fusible Plug from rear

  • Removal of Non-Condensable GassesExistence of Non-Condensable Gasses is the major cause of high discharge pressure. Air and Non-Condensable Gasses collect at the top of receiver Refrigeration reclaim equipment must be connected to the purge valve on the receiver Hose from reclaim equipment must be able to depress Schrader valve Remove small amount of refrigerant through reclaim device Observe discharge pressure for 5 minutes Repeat until discharge pressure is normal, saturated discharge pressure should be 11 to 17 degrees C above the ambient If discharge pressure fails to return to normal, reclaim refrigerant charge, pump system into a vacuum and recharge with refrigerant

  • Refrigerant Leak TestingCheck all joints and fittings The preferred method for leak detection is use of an electronic leak detector Leak testing with soap suds will reveal only larger leaksPortable electronic leak detectors are usually used for field testing

  • Mega-Ohm TestingPurpose: test motor insulation with high Voltage DCA Go-No-go proof test of motor insulationMegger will produce voltage pulse and indicate pass or failUsed to check compressor and fan motors Three basic types: Hand crank, line operated and battery Test Voltage:Device rating up to 100 Vac test voltage is 100 to 250 VdcDevice rating 440 to 550 Vac test voltage is 500 to 1000 VdcDevice rating 2000 Vac test voltage 1000 to 2500 Vdc Caution: Never touch test leads during test and electrically isolate the motor being tested

  • Test ProcedureRecord nameplate information Select test voltage To test insulation between lead and earth ground, connect 1 terminal to the lead and the other to a good earth ground To test between a winding and frame, connect 1 terminal to the lead and 1 terminal to ground Test L1, L2 and L3 For hand crank megger, turn at ~ 160 RPM Megger will indicate pass or fail Record test results, test every 8 to 12 months