Audi Audi S4 1991-1994 HVAC Specifications
Detailed technical specifications and operational details for the HVAC system in the 1991-1994 Audi S4. Includes component descriptions, refrigerant requirements, and troubleshooting tips.
Overview Specifications
Comprehensive description of the HVAC specifications for the 1991-1994 Audi S4, including key features, measurements, and technical details. This documentation covers the heating, ventilation, and air conditioning system, providing detailed insights into its components, performance, and maintenance requirements.
How to Use
Use the search function to locate specific HVAC specifications by entering keywords such as 'blower motor', 'refrigerant capacity', or 'temperature control'. Use exact terms for best results.
Navigate through the HVAC documentation sections using the table of contents. Each section is organized by major components and subsystems, with subsections detailing specific technical information.
Key Specifications
Refrigerant Capacity
850 g
Heater Core Capacity
5.5 kW
Blower Motor Power
200W
Compressor Displacement
120 cc
Airflow Capacity
400 m³/h
Available Specifications
HVAC System Overview
This section provides an overview of the HVAC system, including its major components, operational principles, and key specifications.
HVAC System Overview
This section provides an overview of the HVAC system, including its major components, operational principles, and key specifications.
System Components
- Blower motor with a power rating of 200W
- Evaporator core with a capacity of 1.5 kW
- Heater core with a capacity of 5.5 kW
- Compressor with a displacement of 120 cc
- Refrigerant type: R134a
Operational Principles
- Dual-zone climate control for driver and passenger
- Automatic temperature regulation with ±0.5°C accuracy
- Airflow distribution via 8 adjustable vents
- Recirculation mode for improved cabin air quality
Note: The system uses a combination of mechanical and electronic controls for precise temperature management.
Refrigerant System
This section details the refrigerant system, including specifications for the compressor, condenser, and refrigerant lines.
Refrigerant System
This section details the refrigerant system, including specifications for the compressor, condenser, and refrigerant lines.
Compressor Specifications
- Type: Swash plate compressor
- Displacement: 120 cc
- Maximum pressure: 30 bar
- Lubrication: PAG oil, 150 ml capacity
Refrigerant Capacity
- Total refrigerant capacity: 850 g
- Refrigerant type: R134a
- Operating pressure: 2.5 bar (low side), 15 bar (high side)
- Refrigerant flow rate: 12 L/min
Note: Ensure proper refrigerant levels to avoid system inefficiency or damage.
Heating and Ventilation
This section covers the heating and ventilation components, including the heater core, blower motor, and air distribution system.
Heating and Ventilation
This section covers the heating and ventilation components, including the heater core, blower motor, and air distribution system.
Heater Core
- Heating capacity: 5.5 kW
- Core dimensions: 200 mm x 150 mm x 50 mm
- Coolant flow rate: 8 L/min
- Maximum coolant temperature: 120°C
Blower Motor
- Power rating: 200W
- Speed control: 4-speed settings
- Airflow capacity: 400 m³/h
- Noise level: < 60 dB at maximum speed
Note: The blower motor is controlled via a resistor pack for variable speed settings.
Control System
This section explains the HVAC control system, including the electronic control unit, sensors, and user interface.
Control System
This section explains the HVAC control system, including the electronic control unit, sensors, and user interface.
Electronic Control Unit (ECU)
- Microprocessor: 16-bit, 12 MHz clock speed
- Inputs: Temperature sensors, sun load sensor, cabin air quality sensor
- Outputs: Actuators for blend doors, compressor clutch, and blower motor
- Diagnostics: OBD-I compliant with fault code storage
User Interface
- Dual-zone temperature control with LCD display
- Fan speed control with 4 settings
- Mode selection: Auto, Defrost, Vent, Floor
- Recirculation button for cabin air control
Note: The system includes a self-diagnostic mode accessible via the control panel.
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Component Specifications
General Specifications
- System Type
- Automatic Climate Control
- Refrigerant Type
- R-134a
- Refrigerant Capacity
- 850 grams
- Compressor Type
- Swash Plate Compressor
- Compressor Part Number
- 8D0260805B
- Blower Motor Type
- Brushless DC Motor
- Blower Motor Part Number
- 8D1820011A
Heating System
- Heater Core Material
- Aluminum
- Heater Core Part Number
- 8D1810031A
- Heater Core Flow Rate
- 5.5 liters per minute
- Coolant Temperature Range
- 85°C to 105°C
- Heater Valve Type
- Electrically Controlled
- Heater Valve Part Number
- 8D1819631A
Cooling System
- Evaporator Material
- Aluminum
- Evaporator Part Number
- 8D1820015A
- Evaporator Temperature Range
- 2°C to 10°C
- Condenser Material
- Aluminum
- Condenser Part Number
- 8D1820515A
- Condenser Airflow Requirement
- 600 cubic feet per minute
Air Distribution
- Blower Fan Speed Range
- 3 to 7 speeds
- Blower Fan Power Consumption
- 120 watts
- Airflow Direction Control
- Automatic with Manual Override
- Airflow Distribution Modes
-
- Face
- Floor
- Defrost
- Mix
- Airflow Volume Range
- 150 to 450 cubic feet per minute
Control System
- Control Unit Type
- Digital Microprocessor
- Control Unit Part Number
- 8D1820043A
- Temperature Sensor Type
- NTC Thermistor
- Temperature Sensor Part Number
- 8D1820051A
- Temperature Setting Range
- 16°C to 32°C
- Humidity Sensor Type
- Capacitive
- Humidity Sensor Part Number
- 8D1820052A
Ducting And Vents
- Duct Material
- Polypropylene
- Vent Material
- ABS Plastic
- Vent Part Number
- 8D1820071A
- Duct Diameter Range
- 50mm to 100mm
- Vent Airflow Adjustment
- Manual Slider Control
Filters
- Cabin Filter Type
- Particle and Activated Carbon
- Cabin Filter Part Number
- 8D1820439A
- Cabin Filter Replacement Interval
- 15,000 miles or 12 months
- Filter Efficiency
- 95% for particles > 0.3 microns
Operational Parameters
- System Voltage
- 12V DC
- Maximum System Current
- 15 amps
- Operating Temperature Range
- -30°C to 50°C
- Maximum System Pressure
- 30 bar
- Minimum System Pressure
- 1.5 bar
Diagnostic Specifications
- Diagnostic Port Type
- OBD-I
- Diagnostic Codes
-
- Fault Code 1: Low Refrigerant
- Fault Code 2: Blower Motor Failure
- Fault Code 3: Temperature Sensor Malfunction
- Diagnostic Tool Requirement
- Audi-specific Scan Tool
- Diagnostic interval
- Every 10,000 miles or as needed
Maintenance Specifications
- Refrigerant Recharge interval
- Every 2 years or as needed
- System Leak Check interval
- Every 12 months
- Blower Motor Lubrication interval
- Every 30,000 miles
- Belt Tension Check interval
- Every 15,000 miles
- System Flush interval
- Every 5 years or as needed
Service Information Service
Detailed service requirements and schedules for the HVAC system
- Replace cabin air filter
- Check refrigerant level
- Inspect blower motor and belts
Ensure all connections are secure and free of debris
- Lubricate blower motor bearings
- Check and adjust belt tension
- Inspect ducting for leaks
Use only Audi-approved lubricants and parts
- Flush and recharge refrigerant system
- Inspect and clean evaporator and condenser
- Check all sensors and control units
Perform a full system diagnostic after service
Frequently Asked Questions
Find answers to common questions about torque specifications
Q1 What is the refrigerant type and capacity for the 1991-1994 Audi S4 HVAC system?
What is the refrigerant type and capacity for the 1991-1994 Audi S4 HVAC system?
The 1991-1994 Audi S4 HVAC system uses R-134a refrigerant. The total system capacity is approximately 850-900 grams (30-32 ounces). Always refer to the under-hood label for exact specifications.
Q2 How do I diagnose a lack of airflow from the HVAC system?
How do I diagnose a lack of airflow from the HVAC system?
A lack of airflow can be caused by a faulty blower motor, clogged cabin air filter, or a malfunctioning HVAC control unit. Check the blower motor resistor and fuses first. The cabin air filter should be inspected and replaced every 15,000-20,000 miles or as needed.
Q3 What is the procedure for recharging the HVAC system?
What is the procedure for recharging the HVAC system?
To recharge the HVAC system, first evacuate the system using a vacuum pump to remove moisture and air. Then, recharge with R-134a refrigerant to the specified capacity (850-900 grams). Use a manifold gauge set to monitor pressure levels, ensuring high-side pressure is between 200-250 psi and low-side pressure is between 25-35 psi at optimal operating conditions.
Q4 How do I troubleshoot uneven cooling or heating in the cabin?
How do I troubleshoot uneven cooling or heating in the cabin?
Uneven cooling or heating may indicate a problem with the blend door actuators, a clogged heater core, or low refrigerant levels. Inspect the blend door operation using a diagnostic scan tool. Flush the heater core if necessary and ensure refrigerant levels are within specification.
Q5 What are the common signs of a failing HVAC compressor?
What are the common signs of a failing HVAC compressor?
Common signs include unusual noises (grinding or squealing), reduced cooling performance, and visible refrigerant leaks. The compressor clutch should engage when the AC is turned on. If it does not, check the clutch relay, wiring, and refrigerant pressure.
Factory Service Resources
Access official service manuals, technical documents, and repair guides. These resources provide detailed procedures, specifications, and diagrams directly from the manufacturer.
Audi S4 HVAC System Service Manual
Coming SoonOfficial service manual for the 1991-1994 Audi S4 HVAC system, including detailed repair procedures and specifications.
HVAC Troubleshooting Guide
Coming SoonStep-by-step guide to diagnosing and repairing common HVAC issues in the 1991-1994 Audi S4.
Refrigerant Handling and Safety
Coming SoonComprehensive guide on safe handling, storage, and disposal of R-134a refrigerant, including EPA regulations.
Blower Motor Replacement Procedure
Coming SoonDetailed instructions for replacing the blower motor in the 1991-1994 Audi S4 HVAC system.
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