Technical Service Bulletins (TSBs) for the 2004 Z4 are official communications between BMW & their dealerships that describe processes for troubleshooting or fixing certain common problems. All vehicle manufacturers are required by U.S. law to make their TSBs available to the public.

    STEERING: STEERING WHEEL/HANDLE BAR

    • TSB #B340414

      Date Announced:
      APR 01, 2021
      NHTSA ID:
      #10194296

      Diagnosis of Compound Brake System Complaints in M Vehicles: 1. Visible cracks are caused by high thermal stresses during rapid heating and cooling of the brake discs. Read More »

    STEERING:HYDRAULIC POWER ASSIST SYSTEM

    • TSB #SIB-32-04-07

      Date Announced:
      JUN 01, 2010
      NHTSA ID:
      #10036979

      BMW: A NEW TECHNICAL PROCESS HAS BEEN CREATED FOR BMW TO IDENTIFY CAUSES OF STEERING COMPLAINTS WITH A WIDE RANGE OF MODELS. *RM Read More »

    STEERING:ELECTRIC POWER ASSIST SYSTEM

    • TSB #SIB-32-04-07

      Date Announced:
      JUN 01, 2010
      NHTSA ID:
      #10036979

      BMW: A NEW TECHNICAL PROCESS HAS BEEN CREATED FOR BMW TO IDENTIFY CAUSES OF STEERING COMPLAINTS WITH A WIDE RANGE OF MODELS. *RM Read More »

    SUSPENSION:REAR:AXLE:NON-POWERED AXLE ASSEMBLY

    • TSB #SIB-33-01-02

      Date Announced:
      JUL 01, 2011
      NHTSA ID:
      #10040853

      BMW: A GRINDING NOISE IS COMING FROM THE DIFFERENTIAL DURING SLOW CORNERING. WHEN TURNING A SLIP/STICK EFFECT IS CREATED ON THE LINING AND STEEL DISCS INCORPORATED IN THE DIFFERENTIAL CLUTCH CAUSES A GRINDING NOISE. Read More »

    SERVICE BRAKES, HYDRAULIC

    • TSB #SI-B-34-11-08

      Date Announced:
      AUG 01, 2009
      NHTSA ID:
      #10030844

      BMW VEHICLES: TEILECLEARING FOR DYNAMIC STABILITY CONTROL (DSC). A PART REPLACEMENT AUTHORIZATION MUST BE OBTAINED BY SUBMITTING A TC CASE IN PUMA BEFORE ANY OF THE FOLLOWING DSC COMPONENTS ARE REPLACED UNDER WARRANTY FOR THE VEHICLES ... Read More »

    SERVICE BRAKES, AIR

    • TSB #SI-B-34-11-08

      Date Announced:
      AUG 01, 2009
      NHTSA ID:
      #10030844

      BMW VEHICLES: TEILECLEARING FOR DYNAMIC STABILITY CONTROL (DSC). A PART REPLACEMENT AUTHORIZATION MUST BE OBTAINED BY SUBMITTING A TC CASE IN PUMA BEFORE ANY OF THE FOLLOWING DSC COMPONENTS ARE REPLACED UNDER WARRANTY FOR THE VEHICLES ... Read More »

    SERVICE BRAKES, AIR:DISC

    • TSB #B340414

      Date Announced:
      APR 01, 2021
      NHTSA ID:
      #10194296

      Diagnosis of Compound Brake System Complaints in M Vehicles: 1. Visible cracks are caused by high thermal stresses during rapid heating and cooling of the brake discs. Read More »

    ENGINE AND ENGINE COOLING

    • TSB #SI B12 55 06

      Date Announced:
      JAN 01, 2011
      NHTSA ID:
      #10037700

      BMW: THERE MAY BE EXCESSIVE CRANKING BEFORE THE VEHICLE STARTS. THE SERVICE ENGINE SOON LIGHT MAY ALSO BE ON WITH A LACK OF ENGINE POWER. *RM Read More »

    • TSB #SI B12 12 10

      Date Announced:
      JUN 01, 2010
      NHTSA ID:
      #10037702

      BMW: WHEN AT LOWER SPEEDS OR STOPPING THE ENGINE IDLE DIPS TOO LOW BECAUSE OF A SOFTWARE PROBLEM. *RM Read More »

    • TSB #121104

      Date Announced:
      FEB 01, 2004
      NHTSA ID:
      #10012782

      RETROFIT THE POWER SUPPLY CABLE FOR THE THERMAL OIL LEVEL SENSOR. *EH Read More »

    ENGINE AND ENGINE COOLING:ENGINE

    • TSB #SI-B-12-04-05

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10028370

      BMW: CHECK ENGINE LAMP ILLUMINATED AND/OR VEHICLE OVERHEATS. MODELS E83, E85, E86, E70, E90, E91, E92, E93, E60 AND E61. *PE UPDATED 5/24/11. *PE Read More »

    • TSB #SI B12-55-06

      Date Announced:
      JUL 01, 2010
      NHTSA ID:
      #10025701

      N54-DIAGNOSIS FOR DME FC 29DC/2FBF FOR MODELS E90, E92 PRODUCED FROM 06/06 AND E93, E60, E61 PRODUCED FROM 03/07. *PE UPDATED 7/8/09. *PE MODELS E82, E88 PRODUCED FROM START 2000 AND E71 PRODUCED FROM START 2000. Read More »

    • TSB #SIB-11-08-03

      Date Announced:
      JUL 01, 2010
      NHTSA ID:
      #10037010

      BMW: SIX DIFFERENT MODELS EQUIPPED WITH THE M54 ENGINE COULD HAVE VALVE COVERS BREAK IN COLD WEATHER AND RUIN THE ENGINE. THIS IS DUE TO MOISTURE ACCUMULATION. *RM Read More »

    • TSB #SIB-12-20-07

      Date Announced:
      NOV 01, 2007
      NHTSA ID:
      #10032812

      BMW VEHICLE: M54/M56-MIXTURE TOO LEAN-FAULT CODES 2882/2883 ARE STORED IN THE DME. COMPLAINTS THAT SERVICE ENGINE SOON LIGHT IS ILLUMINATED. THE FAULT CODES 2882/2883-FUEL TRIM, MIXTURE TOO LEAN ARE STORED IN THE DME. Read More »

    • TSB #04V182

      Date Announced:
      APR 19, 2004
      NHTSA ID:
      #10007032

      RECALL CAMPAIGN 04V-182 ENGINE STALLING. *TT Read More »

    • TSB #04V182

      Date Announced:
      APR 19, 2004
      NHTSA ID:
      #10007263

      RECALL CAMPAIGN 04V-182 ENGINE STALLING. CORRECTED PRODUCTION DATES. *TT Read More »

    • TSB #041904

      Date Announced:
      APR 09, 2004
      NHTSA ID:
      #10007033

      RECALL CAMPAIGN 04V182 - ENGINE STALLING. CORRECTION PRODUCTION DATES. *TT Read More »

    ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR

    • TSB #SIB-12-24-07

      Date Announced:
      NOV 01, 2007
      NHTSA ID:
      #10032814

      BMW VEHICLE: S54-CATALYST PROTECTION MODE WHILE THE VEHICLE IS LOW ON FUEL. COMPLAINTS THAT THE VEHICLE HAS NO POWER DURING HEAVY ACCELERATION. Read More »

    FUEL SYSTEM, GASOLINE

    • TSB #SIB-12-24-07

      Date Announced:
      NOV 01, 2007
      NHTSA ID:
      #10032814

      BMW VEHICLE: S54-CATALYST PROTECTION MODE WHILE THE VEHICLE IS LOW ON FUEL. COMPLAINTS THAT THE VEHICLE HAS NO POWER DURING HEAVY ACCELERATION. Read More »

    FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY

    • TSB #SIB-12-24-07

      Date Announced:
      NOV 01, 2007
      NHTSA ID:
      #10032814

      BMW VEHICLE: S54-CATALYST PROTECTION MODE WHILE THE VEHICLE IS LOW ON FUEL. COMPLAINTS THAT THE VEHICLE HAS NO POWER DURING HEAVY ACCELERATION. Read More »

    FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP

    • TSB #SIB-16-02-09

      Date Announced:
      DEC 01, 2009
      NHTSA ID:
      #10033130

      BMW VEHICLES: FUEL LEVEL SENSOR REPAIRS. WHERE IT IS NECESSARY TO REPLACE THE RIGHT OR THE LEFT SIDE FUEL LEVEL SENSOR DUE TO A FAILURE, THE ENTIRE PUMP AND HOUSING OR DELIVERY UNIT (SUCTION JET ASSEMBLY) DO NOT NEED TO BE REPLACED AS ... Read More »

    FUEL SYSTEM, OTHER:FUEL FILTER

    • TSB #SIB-12-20-07

      Date Announced:
      NOV 01, 2007
      NHTSA ID:
      #10032812

      BMW VEHICLE: M54/M56-MIXTURE TOO LEAN-FAULT CODES 2882/2883 ARE STORED IN THE DME. COMPLAINTS THAT SERVICE ENGINE SOON LIGHT IS ILLUMINATED. THE FAULT CODES 2882/2883-FUEL TRIM, MIXTURE TOO LEAN ARE STORED IN THE DME. Read More »

    POWER TRAIN

    • TSB #B110208

      Date Announced:
      APR 01, 2020
      NHTSA ID:
      #10175267

      Power Reduction FC2A82 Intake VANOS and/or FC2 A87 Exhaust VANOS Camshaft Fault: The "Service Engine Soon" (MIL) lamp is illuminated and engine power reduction is perceived. Read More »

    POWER TRAIN:MANUAL TRANSMISSION

    • TSB #SIB-28-02-08

      Date Announced:
      JUN 01, 2010
      NHTSA ID:
      #10036980

      BMW: A NEW TECHNICAL PROCESS IS BEING USED ON MANY MODELS TO DETERMINE THE ROOT CAUSE OF DOUBLE-CLUTCH TRANSMISSION PROBLEMS. *RM Read More »

    POWER TRAIN:AUTOMATIC TRANSMISSION

    • TSB #SIB-23-01-08

      Date Announced:
      APR 01, 2011
      NHTSA ID:
      #10040045

      BMW: A NEW TECHNICAL SUPPORT PROCESS HAS BEEN CREATED REGARDING TRANSMISSION CONCERNS. *RM Read More »

    ELECTRICAL SYSTEM

    • TSB #B510819

      Date Announced:
      JAN 16, 2024
      NHTSA ID:
      #10249437

      The basic conditions for initializing the power windows are not met. Read More »

    • TSB #B611305

      Date Announced:
      JAN 11, 2024
      NHTSA ID:
      #10249027

      The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. Read More »

    • TSB #B611305

      Date Announced:
      OCT 01, 2020
      NHTSA ID:
      #10182619

      Discharged Battery Energy Diagnosis Must Be Performed: The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. Read More »

    • TSB #B110208

      Date Announced:
      APR 01, 2020
      NHTSA ID:
      #10175267

      Power Reduction FC2A82 Intake VANOS and/or FC2 A87 Exhaust VANOS Camshaft Fault: The "Service Engine Soon" (MIL) lamp is illuminated and engine power reduction is perceived. Read More »

    • TSB #513608

      Date Announced:
      JUL 10, 2019
      NHTSA ID:
      #10162404

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    • TSB #610314

      Date Announced:
      JUL 01, 2014
      NHTSA ID:
      #10148120

      Check Control Messages Related to Battery Charge During Cold Ambient Temperatures. On cold days with an outside ambient temperature of less than 15?F, customers may notice a check control message related to the battery that is displayed ... Read More »

    • TSB #610314

      Date Announced:
      APR 01, 2014
      NHTSA ID:
      #10148273

      Check Control Messages Related to Battery Charge During Cold Ambient Temperatures. On cold days with an outside ambient temperature of less than 15F, customers may notice a check control message related to the battery that is displayed on ... Read More »

    • TSB #513608

      Date Announced:
      NOV 01, 2013
      NHTSA ID:
      #10150173

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    • TSB #641105

      Date Announced:
      MAY 01, 2013
      NHTSA ID:
      #10149612

      Clicking/Popping Noise from Dash at Startup. The customer states that when the vehicle is started, or the ignition switch is turned on, there is a clicking/popping noise coming from the dash area. Read More »

    • TSB #SI-B-12-04-05

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10028370

      BMW: CHECK ENGINE LAMP ILLUMINATED AND/OR VEHICLE OVERHEATS. MODELS E83, E85, E86, E70, E90, E91, E92, E93, E60 AND E61. *PE UPDATED 5/24/11. *PE Read More »

    • TSB #SI B12-55-06

      Date Announced:
      JUL 01, 2010
      NHTSA ID:
      #10025701

      N54-DIAGNOSIS FOR DME FC 29DC/2FBF FOR MODELS E90, E92 PRODUCED FROM 06/06 AND E93, E60, E61 PRODUCED FROM 03/07. *PE UPDATED 7/8/09. *PE MODELS E82, E88 PRODUCED FROM START 2000 AND E71 PRODUCED FROM START 2000. Read More »

    ELECTRICAL SYSTEM:12V/24V/48V BATTERY

    • TSB #SIB-61-13-05

      Date Announced:
      MAR 01, 2013
      NHTSA ID:
      #10052012

      BMW: BATTERY HAS AN INCREASED DEMAND DUE TO DEVELOPEMENTAL PROCESS OF THE ELECTRICAL SYSTEM. THIS IS CAUSING THE BATTER TO NEED TO UNDERGO AN ENERGY DIAGNOSIS. *KB Read More »

    ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL

    • TSB #SI-B-12-04-05

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10028370

      BMW: CHECK ENGINE LAMP ILLUMINATED AND/OR VEHICLE OVERHEATS. MODELS E83, E85, E86, E70, E90, E91, E92, E93, E60 AND E61. *PE UPDATED 5/24/11. *PE Read More »

    EXTERIOR LIGHTING

    • TSB #SIB-63-14-10

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10041281

      BMW: THE REAR LAMP IS NOT WATER TIGHT DUE TO CRACKS DUE TO STRESS. WATER MAY ENTER THE LAMP. *RM Read More »

    • TSB #SIB-63-02-01

      Date Announced:
      AUG 01, 2010
      NHTSA ID:
      #10037025

      BMW: PROCEDURE FOR DETERMINING AND REPLACING INCANDESCENT AND HALOGEN LIGHT BULBS UNDER WARRANTY. *RM Read More »

    EXTERIOR LIGHTING:TAIL LIGHTS

    • TSB #SIB-63-14-10

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10041281

      BMW: THE REAR LAMP IS NOT WATER TIGHT DUE TO CRACKS DUE TO STRESS. WATER MAY ENTER THE LAMP. *RM Read More »

    VISIBILITY

    • TSB #513608

      Date Announced:
      NOV 01, 2013
      NHTSA ID:
      #10150173

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    • TSB #513608

      Date Announced:
      AUG 01, 2013
      NHTSA ID:
      #10150224

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    • TSB #513608

      Date Announced:
      FEB 01, 2013
      NHTSA ID:
      #10149441

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    VISIBILITY:POWER WINDOW DEVICES AND CONTROLS

    • TSB #B510819

      Date Announced:
      JAN 16, 2024
      NHTSA ID:
      #10249437

      The basic conditions for initializing the power windows are not met. Read More »

    VISIBILITY:REARVIEW MIRRORS/DEVICES:EXTERIOR

    • TSB #513608

      Date Announced:
      JUL 10, 2019
      NHTSA ID:
      #10162404

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    AIR BAGS

    • TSB #010914

      Date Announced:
      SEP 01, 2014
      NHTSA ID:
      #10148018

      "?SI B01 09 14 September 2014 WarrantiesWarranties This Service Information bulletin supersedes SI B01 09 14 dated August 2014. Please read this Service Information bulletin in its entirety, the content has been completely updated. Read More »

    • TSB #SIB-65-75-06

      Date Announced:
      AUG 01, 2011
      NHTSA ID:
      #10029605

      BMW SERVICE CAMPAIGN: SEE DOCUMENT SEARCH BUTTON FOR OWNER LETTER. THE AIRBAG WARNING LAMP (AWL) IS ILLUMINATED, TOGETHER WITH THE PASSENGER AIRBAG STATUS LAMP (POL). THE PROBLEM MAY BE INTERMITTENT. MICROCRACKS IN THE OC3 SEAT MAT. Read More »

    SEAT BELTS:FRONT

    • TSB #SI-B72-02-09

      Date Announced:
      AUG 01, 2009
      NHTSA ID:
      #10030843

      BMW: BELT TENSIONER HARNESSES. A REPAIR HARNESS FOR THE FRONT SEAT SAFETY BELT TENSIONERS AT THE BELT RETRACTORS MAY HAVE BEEN IMPROPERLY INSTALLED. *PE Read More »

    SEAT BELTS:FRONT:RETRACTOR

    • TSB #SI-B72-02-09

      Date Announced:
      AUG 01, 2009
      NHTSA ID:
      #10030843

      BMW: BELT TENSIONER HARNESSES. A REPAIR HARNESS FOR THE FRONT SEAT SAFETY BELT TENSIONERS AT THE BELT RETRACTORS MAY HAVE BEEN IMPROPERLY INSTALLED. *PE Read More »

    STRUCTURE

    • TSB #513608

      Date Announced:
      NOV 01, 2013
      NHTSA ID:
      #10150173

      "Outside Door Mirror Moves when Locking or Unlocking the Vehicle. The door mirror tilts immediately after unlocking or locking. The mirror position does not correspond to the memory position preset by the customer. Read More »

    STRUCTURE:FRAME AND MEMBERS

    • TSB #SIB-51-42-10

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10037464

      BMW: WATER IS LEAKING INTO THE LUGGAGE COMPARTMENT DUE TO A DAMAGED SEAL ON REAR VENTS. *RM Read More »

    STRUCTURE:BODY

    • TSB #SIB-51-42-10

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10037464

      BMW: WATER IS LEAKING INTO THE LUGGAGE COMPARTMENT DUE TO A DAMAGED SEAL ON REAR VENTS. *RM Read More »

    STRUCTURE:BODY:TRUNK LID

    • TSB #SIB-51-42-10

      Date Announced:
      NOV 01, 2010
      NHTSA ID:
      #10037464

      BMW: WATER IS LEAKING INTO THE LUGGAGE COMPARTMENT DUE TO A DAMAGED SEAL ON REAR VENTS. *RM Read More »

    TIRES:VALVE

    • TSB #B360215

      Date Announced:
      MAY 01, 2015
      NHTSA ID:
      #10147136

      Valve Stem Replacement with Wheel Electronics. INFORMATION The valve stems are single-use only, and must be replaced every time the wheel electronics are replaced. If you loosen the nut (1), you must replace the valve stem. Read More »

    WHEELS

    • TSB #B360215

      Date Announced:
      MAY 01, 2015
      NHTSA ID:
      #10147136

      Valve Stem Replacement with Wheel Electronics. INFORMATION The valve stems are single-use only, and must be replaced every time the wheel electronics are replaced. If you loosen the nut (1), you must replace the valve stem. Read More »

    EQUIPMENT

    • TSB #B611305

      Date Announced:
      OCT 01, 2020
      NHTSA ID:
      #10182619

      Discharged Battery Energy Diagnosis Must Be Performed: The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. Read More »

    • TSB #010914

      Date Announced:
      SEP 01, 2014
      NHTSA ID:
      #10148018

      "?SI B01 09 14 September 2014 WarrantiesWarranties This Service Information bulletin supersedes SI B01 09 14 dated August 2014. Please read this Service Information bulletin in its entirety, the content has been completely updated. Read More »

    • TSB #610314

      Date Announced:
      APR 01, 2014
      NHTSA ID:
      #10148273

      Check Control Messages Related to Battery Charge During Cold Ambient Temperatures. On cold days with an outside ambient temperature of less than 15F, customers may notice a check control message related to the battery that is displayed on ... Read More »

    • TSB #120913

      Date Announced:
      NOV 01, 2013
      NHTSA ID:
      #10150160

      State Inspection and Emission (I/M) Test Fails Due To an Invalid VIN Number. The customer of an affected vehicle may fail to pass an I/M test due to a non-compliant 17digit vehicle identification number (VIN) stored in the DME (Digital ... Read More »

    EQUIPMENT:ELECTRICAL

    • TSB #B662419

      Date Announced:
      SEP 01, 2022
      NHTSA ID:
      #10225126

      Vehicle cannot be opened or closed using comfort access, engine start is not possible, and the vehicle may not start when placing the key against the steering column. Read More »

    EQUIPMENT:ELECTRICAL:NAVIGATIONAL SYSTEM(GLOBAL POSITIONING SYSTEM)

    • TSB #B650709

      Date Announced:
      JUN 01, 2018
      NHTSA ID:
      #10145306

      NAVIGATION SYSTEM: REPORTING MISSING OR INCORRECT ROAD MAP DATA: The route guidance is inaccurate and therefore irritating to the customer; or it is not possible to locate certain addresses, for ... Read More »

    • TSB #B650709

      Date Announced:
      MAY 01, 2018
      NHTSA ID:
      #10143564

      NAVIGATION SYSTEM: REPORTING MISSING OR INCORRECT ROAD MAP DATA: The route guidance is inaccurate and therefore irritating to the customer; or it is not possible to locate certain addresses, for ... Read More »

    EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL

    • TSB #010914

      Date Announced:
      SEP 01, 2014
      NHTSA ID:
      #10148018

      "?SI B01 09 14 September 2014 WarrantiesWarranties This Service Information bulletin supersedes SI B01 09 14 dated August 2014. Please read this Service Information bulletin in its entirety, the content has been completely updated. Read More »

    EQUIPMENT ADAPTIVE/MOBILITY

    • TSB #B611305

      Date Announced:
      OCT 01, 2020
      NHTSA ID:
      #10182619

      Discharged Battery Energy Diagnosis Must Be Performed: The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. Read More »

    • TSB #610314

      Date Announced:
      APR 01, 2014
      NHTSA ID:
      #10148273

      Check Control Messages Related to Battery Charge During Cold Ambient Temperatures. On cold days with an outside ambient temperature of less than 15F, customers may notice a check control message related to the battery that is displayed on ... Read More »

    EQUIPMENT:APPLIANCE:AIR CONDITIONER

    • TSB #B650709

      Date Announced:
      JAN 01, 2016
      NHTSA ID:
      #10151023

      Whistling Noise Coming from the Center Vent - A/C is Off . A very high pitched whistling or beeping noise is heard coming from the center vents. The flow of refrigerant through the expansion valve at certain temperature differentials. Read More »