Automatic A/c-Heater Systems BMW M3 E36

SPECIFICATIONS

SPECIFICATIONS

DESCRIPTION

The A/C-heater system automatically adjusts passenger compartment temperatures via control unit and A/C-heater control panel. (Scheme 1) A/C-heater control unit regulates heater operation through an electromagnetic water valve. The electromagnetic water valve controls flow rate through heater core.

Air temperature is regulated by mixing varying ratios of cold and heated air through a cable operated temperature mixing flap. Temperature and air distribution for driver-side and front passenger-side can be controlled separately. All outlets can supply heated, cooled or fresh air according to temperature control knob setting. (Scheme 2)

System uses 6 input sensors for operation: outside temperature sensor, inside temperature sensor, heater core temperature sensor (driver and passenger-side), evaporator temperature sensor and interior temperature sensor. Temperature sensors continuously input information to A/C-heater control unit. A/C-heater control unit processes sensor signals and adjusts system temperature accordingly.

Scheme 1

Air Conditioning Button

Air conditioning is switched on by push button located to right of blower control knob. (Scheme 1) A/C system will operate only at temperatures greater than 37°F (3°C) with engine on. At least one air outlet must be open when operating A/C system, to prevent evaporator freeze-up.

Air Distribution Control Knob

Rotary motion of control knob varies amount of air to defroster, footwell and instrument panel outlets. Defrost is controlled by temperature and blower controls. An illustration below temperature control knobs shows settings for maximum defrost.

Blower Control Knob

Blower control knob allows volume of air entering passenger compartment to be varied. Airflow increases as knob is turned clockwise. Airflow decreases automatically at speeds greater than 50 MPH. When A/C switch is turned on with blower control knob in "0" position, a small amount of air will continue to enter passenger compartment. Blower control knob has 5 positions, and allows 4 different blower motor speed settings.

Recirculated Air Button

Pushing recirculated air button cuts off outside air flow.

Temperature Control Knob

Temperature control knobs determine temperature of air entering driver-side or passenger-side compartment. Turning control knob clockwise will increase air temperature. Selected air temperature will stabilize within passenger compartment shortly thereafter.

Scheme 2

COMPONENT LOCATIONS

COMPONENT LOCATIONS

SELF-DIAGNOSTIC SYSTEM

Note. A/C control unit is capable of storing intermittent or permanent defects in memory. Diagnosis of such defects can be found using BMW Service Tester (Sun 2013 Engine Analyzer) and applicable BMW diagnostic software. See FAULT CODE IDENTIFICATION .

DIAGNOSTIC TROUBLE CODE DEFINITIONS

FAULT CODE IDENTIFICATION

REMOVAL & INSTALLATION

1. Insert a feeler gauge between on-board display frame and lower shelf to push back locking lever(s). Carefully pry out on-board display. Disconnect wiring harness and remove on-board display.
2. Carefully pry out lower shelf and set aside. Remove A/C-heater control panel knobs. Remove screws from A/C-heater control panel, and carefully pry off trim panel.
3. Push A/C-heater control panel back and guide panel down to on-board display opening. Disconnect wiring harness and remove A/C-heater control panel. To install, reverse removal procedure.

Removal

1. Disconnect negative battery cable. Pull rubber sealing strip from cowl/firewall. Remove air intake grille. Remove screws attaching wiring harness to heater cover, and pull wiring out of way.
2. Remove air intake duct bolts, and remove air intake duct. If necessary, remove engine covers. If necessary, remove wiring harness cover and disconnect wiring harnesses from control units (on right front fender).
3. Loosen clips and remove blower motor cover. (Scheme 3) Disconnect wiring harness connectors from blower motor. Disengage clips and lift left flap upper section up. Cut off blower motor wheels at brace and carefully lift out blower motor.

Installation

To install, reverse removal procedure. Ensure all seals are installed correctly.

Scheme 3

1. Discharge A/C system, using approved refrigerant recovery/ recycling equipment. Pull rubber sealing strip from cowl/firewall. Remove air intake grille. Remove screws attaching wiring harness to heater cover, and pull wiring out of way.
2. Remove air intake duct bolts, and remove air intake duct. If necessary, remove engine covers. Drain cooling system. Disconnect heater hoses at heater core flange. Remove heater brackets from cowl/firewall. Disconnect and plug refrigerant lines.
3. Remove air outlet grilles from instrument panel. Loosen clips and remove glove box. Remove trim from "A" pillars. Remove trim panels from right and left sides of instrument panel.
4. Lower steering column. See «STEERING COLUMN»(/bmw/m3/e36-1992-1999/remont/automatic-hvac-system/#automatic-ac-heater-systems) . Remove 3 instrument cluster screws. Carefully pull out instrument cluster. Raise wiring harness connector levers on back of instrument cluster and disconnect wiring harness. Remove instrument cluster.
5. Remove shift lever dust cover. Remove hazard light warning switch and rear ashtray. Remove screws and parking brake lever console. Remove screws and lift out center console.
6. Remove bolts from ends of instrument panel. Ensure all wiring harnesses are disconnected. Carefully remove instrument panel. Pry out control unit, and disconnect it from wiring harness.
7. Cut wiring harness straps and remove reinforcement pipe for steering column. Cut wiring harness strap and disconnect wiring harness from A/C-heater unit. Remove bolts and A/C-heater unit.

To install, reverse removal procedure. Ensure wiring harnesses are not pinched during installation. Replace heater core flange "O" rings. It may be necessary to recode instrument cluster (dealership procedure only). Check A/C-heater system for proper operation.

1. Disconnect negative battery cable. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove engine splash shield. Disconnect compressor clutch electrical connectors.
2. Loosen A/C compressor belt tensioner bolt(s) to relieve belt tension, and remove A/C compressor belt. Remove refrigerant hose couplings. Plug refrigerant lines. Remove compressor bolts, and remove A/C compressor.

To install, reverse removal procedure. Check compressor oil level. Evacuate, charge, and leak test A/C system.

Condenser

Note. Use Pulley Holder (11 5 050 on 318 Series or 11 5 030 on 325 Series) to hold radiator (cooling) fan pulley. Turn 32-mm Wrench (11 5 040) clockwise to remove cooling fan. Cooling fan nut uses left-hand threads.

Remove radiator fan. Remove radiator from vehicle. Remove radiator right grille section. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect and cap refrigerant lines at condenser. Remove condenser bolts. Remove condenser from above.

To install condenser, reverse removal procedure. Use new line coupling seals. Charge A/C system, and check for proper operation. Tighten cooling fan pulley nut to 22 ft. lbs. (30 N.m) if using 32-mm Wrench (11 5 040). Tighten nut to 29 ft. lbs. (40 N.m) if a conventional 32-mm wrench is used.

1. Pull rubber sealing strip from cowl/firewall. Remove air intake grille. Remove screws attaching wiring harness to heater cover, and pull wiring out of way.
2. Remove air intake duct bolts, and remove air intake duct. If necessary, remove engine covers. Drain cooling system. Disconnect heater hoses at heater core flange.
3. Inside passenger compartment, remove screws from passenger-side trim panel. Carefully pry out trim panel from end of instrument panel. Remove screw and remove heater core.

To install, reverse removal procedure. Fill cooling system and check for leaks.

1. Disconnect negative battery cable. Remove package tray. Remove instrument panel trim on left side. Discharge A/C system using approved refrigerant recovery/recycling equipment. Open glove box. Unscrew bolt, and remove glove box trim.
2. Disconnect pins of straps. Loosen nuts, and remove glove box. Disconnect refrigerant lines from evaporator and plug. Remove blower motor cover.
3. Disconnect temperature switch and capillary tube sensor connectors from evaporator. Unscrew evaporator assembly bolts. Simultaneously remove temperature switch and sensor from evaporator housing. Pull evaporator from housing.

To install, reverse removal procedure. Use new line coupling seals. Wrap refrigerant lines with insulating tape after installation.

1. Disable air bag system. See AIR BAG RESTRAINT SYSTEM article in ACCESSORIES/SAFETY EQUIPMENT SECTION. Ensure steering wheel is in straight-ahead position.
2. Unlock bayonet mount at base of steering column by turning it counterclockwise. Remove screw and lower cover on steering column. Remove bolt from steering column universal joint. Remove sheared off screws, and lower steering column. To install, reverse removal procedure.

Refer to A/C-HEATER CONTROL PANEL and HEATER CORE for removal and installation procedure. (Scheme 4)

Scheme 4

Removal and installation procedure is not available from manufacturer. As a guide (Scheme 4)

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

PIN VOLTAGE CHARTS

Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at the A/C-heater control unit determines whether it is receiving and transmitting proper voltage signals. Charts may also help determine if A/C-heater control unit wiring harness has a short or open circuit.

Note. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance.

A/C-HEATER CONTROL PANEL PIN ASSIGNMENTS (1)

A/C-HEATER CONTROL UNIT PIN ASSIGNMENT (BLACK CONNECTOR) (1)

A/C-HEATER CONTROL UNIT PIN ASSIGNMENTS (BLUE CONNECTOR) (1)

A/C-HEATER CONTROL UNIT PIN ASSIGNMENTS (WHITE CONNECTOR) (1)

Automatic A/C-Heater System Schematic (1994-95 - 1 Of 2). Scheme 5

Automatic A/C-Heater System Schematic (1994-95 - 2 Of 2). Scheme 6

Automatic A/C-Heater System Schematic (1995 318ti). Scheme 7

See also:
• FAULT CODE IDENTIFICATION