Component Functions and Specifications
Note
^ Replacement A/C compressors supplied by the Parts Department are filled with 250 cc (8.5 fl oz) of A/C refrigerant (PAG) oil. This is the total A/C system refrigerant oil capacity
^ Do Not top-off a charged refrigerant system. Instead, discharge, evacuate and recharge system.
^ Only use new O-rings specified for use with R-134a.
^ O-ring and torque specifications also apply to threaded connections in the A/C lines.
^ Components 6a and 7a shown in illustration 87-1416 are installed only on vehicles equipped with a 5-cylinder engine and do not apply to USA and Canada.
1 - COMPRESSOR (Zexel)
The compressor is driven via a belt on the engine when the A/C clutch engages (A/C ON).
The variable displacement A/C compressor varies piston stroke and output depending on load requirements and suction pressure.
Low pressure refrigerant gas from the evaporator is compressed by the compressor. After compression, the refrigerant gas (now high pressure) flows to the condenser.
^ O-ring seal:
Low pressure connection:
17.2 mm inside diameter
1.8 mm thickness
High pressure connection:
14.0 mm inside diameter
1.8 mm thickness
^ Torque:
Low pressure connection:
40 Nm (29.5 ft lb)
High pressure connection:
30 Nm (22.1 ft lb)
CAUTION
Mark travel direction of ribbed drive belt before removing. Reversing direction could cause the belt to fail.
If a new A/C compressor is installed, or if oil was added to compressor, manually rotate compressor 10 times before operating the system to prevent compressor damage.
Ensure A/C compressor refrigerant lines are properly insulated from exhaust system heat.
Note
^ The compressor contains refrigerant oil (PAG oil) that is mixable under all temperatures with R-134a refrigerant.
^ A label on the compressor indicates that compressor is for R-134a systems only
2 - SPEED SENSOR
- inductive sensor (4 pulses per compressor rotation)
- determines A/C compressor speed; the A/C compressor clutch control module (Manual A/C) or the A/C control head (Automatic climate control) compares compressor speed to engine speed and calculates belt slippage (as a percentage) and switches compressor OFF if slippage is too much (for example, if belt is too loose.)
^ 0-ring seal*:
15.5 mm inside diameter
1.5 mm thickness
* Original equipment 0-ring may be black in color. When replacing, use 0-ring specified by Parts information
CAUTION
Discharge A/C system before removing A/C compressor speed sensor.
3 - A/C CLUTCH
4 - OIL DRAIN PLUG
^ 0-ring seal*:
7.8 mm inside diameter
1.9 mm thickness
* Original equipment 0-ring may be black in color. When replacing, use 0-ring specified by Parts information
^ Torque: 10 Nm (7.4 ft lb)
Note
Only remove drain plug with compressor removed from vehicle. Use drain plug to drain/add oil to compressor and to check amount of oil in compressor.
5 - PRESSURE RELIEF VALVE
The pressure relief valve is mounted on the compressor. At approx. 38 bar (551 psi), the valve opens to vent excessive pressure. When system pressure is reduced to approx. 30-35 bar (435-508 psi), the valve closes to prevent total refrigerant loss.
^ 0-ring seal*:
8.8 mm inside diameter
1.9 mm thickness
* Original equipment 0-ring may be black in color. When replacing, use 0-ring specified by Parts information
^ Torque: 10 Nm (74 ft lb)
CAUTION
Discharge A/C system before removing pressure relief valve.
6 - HIGH PRESSURE SWITCH (F 118)
Function
Switches A/C clutch OFF if system pressure is too high.
^ Switch identification: red housing with bonded wire connections
^ Switching pressures: Opens (compressor OFF): 28.2-31.0 bar (409-450 psi) Closes (compressor ON): 10.3-17.2 bar (149-250 psi)
^ 0-ring seal:
7.6 mm inside diameter
1.8 mm thickness
^ Torque: 5 Nm (44 in. lb)
6a - Not used on USA/Canada vehicles
Note
The A/C system switches are available in different versions. Always consult the proper parts information to ensure correct switch application.
7 - CONNECTION WITH SCHRADER VALVE
^ For A/C refrigerant high pressure switch
7a - Not used on USA/Canada vehicles
8 - CONDENSER
The condenser transfers heat from the compressed refrigerant gas to the outside air which causes the refrigerant to change state from a gas to a liquid.
Note
Illustration shows the condenser from an Audi 100 model.
^ 0-ring seal inlet:
14.0 mm inside diameter
1.8 mm thickness
^ 0-ring seal outlet:
7.6 mm inside diameter
1.8 mm thickness
^ Torque:
Inlet: 30 Nm (22.1 ft lb)
Outlet: 15 Nm (11.0 ft lb)
9 - HIGH PRESSURE SERVICE VALVE
^ used for checking system pressure, discharging, evacuating and recharging system
NOTE
- Use only the specified R-134a quick coupling connectors when servicing the refrigerant system.
- Before removing the valve insert from the high pressure service valve, discharge A/C refrigerant system.
- Always reinstall cap -D- over service valve.
Assembly
A - Service valve connection (soldered to front of condenser)
B - Schrader valve insert
C - O-ring seal
D - Cap with seal
Note
Illustration shows the condenser from an Audi 100 model.
Only a high pressure service valve is used for A/C system servicing. A low pressure service valve is not installed in the A/C system. Perform all A/C system service operations (i.e discharging, evacuating, and charging) through the high pressure service valve only.
10 - CAP, with seal
^ always reinstall over service valve
11 - CONNECTION, with Schrader Valve
^ For A/C refrigerant high pressure switch
12 - HIGH PRESSURE SWITCH (F 23)
^ Switches coolant fan to second speed when A/C system pressure increases.
^ Switch identification:
green housing with bonded wire connections
^ Switching pressures:
Closes (coolant fan 2nd speed ON): 14.2-17.4 bar (206-252 psi)
Opens (coolant fan 2nd speed OFF): 11.7-15.0 bar (170-218 psi)
^ Opening and closing switching points must be at least 2 bar (29 psi) difference
^ O-ring seal:
7.6 mm inside diameter
1.8 mm thickness
^ Torque:
5 Nm (44 in.lb)
Note
The A/C system switches are available in different versions. Always consult the proper parts information to ensure correct switch application.
13 - RESTRICTOR
The restrictor restricts and controls refrigerant flow to the evaporator thus lowering refrigerant temperature and pressure.
Upstream of the restrictor, the refrigerant is hot and under high pressure. Downstream of the restrictor, the refrigerant is cold and under low pressure.
A strainer located upstream of the restrictor filters out any dirt or particles. Another strainer located downstream of the restrictor atomizes the refrigerant before it enters the evaporator.
^ O-ring seal:
7.5 mm inside diameter
1.5 mm thickness
Note
Insert restrictor into evaporator in direction of Arrow -A-.
Illustration shows the evaporator from an Audi 90 model.
14 - EVAPORATOR
Liquid refrigerant entering the evaporator absorbs heat from air passing through the evaporator fins and cools the air. As the refrigerant absorbs heat it turns to vapor and then is suctioned by the compressor.
^ 0-ring seal inlet:
10.8 mm inside diameter
1.8 mm thickness
^ 0-ring seal outlet:
17.2 mm inside diameter
1.8 mm thickness
^ Torque (evaporator line retaining bracket): 15 Nm (11.0 ft lb)
Note
Illustration shows the evaporator from an Audi 90 model.
15 - CONNECTION with Schrader valve
^ inaccessible with evaporator installed
16 - CAP, with seal
^ always reinstall over valve
17 - CONNECTION with Schrader valve
^ For A/C refrigerant low pressure switch
18 - LOW PRESSURE SWITCH
^ Switches A/C clutch OFF if system suction pressure is too low (low refrigerant charge). This switch protects the compressor if the refrigerant system is empty.
^ Switching pressures: Opens (compressor OFF): 1.45-1.6 bar (21-23 psi) Closes (compressor ON): 2.9-3.4 bar (42-49 psi)
^ O-ring seal:
8.9 mm inside diameter
1.8 mm thickness
^ Torque: 5 Nm (44 in. lb)
Note
The A/C system switches are available in different versions. Always consult the proper parts information to ensure correct switch application.
19 - ACCUMULATOR
The accumulator traps the mixture of refrigerant vapor and gas coming from the evaporator. While in the accumulator, the refrigerant vapor turns to gas and, along with the refrigerant oil, is then suctioned by the compressor.
An oil extraction passage is incorporated into the accumulator to ensure that refrigerant oil flowing with the refrigerant does not remain in the accumulator.
Any moisture in the system is absorbed by the desiccant in the accumulator.
Note
Do not remove caps -A- and -B- until ready to install new accumulator. If caps are removed too soon the desiccant becomes saturated with moisture after a very short time. If this occurs, the accumulator
^ O-ring seal inlet:
17.2 mm inside diameter
1.8 mm thickness
^ O-ring seal outlet:
17.2 mm inside diameter
1.8 mm thickness
^ Torque:
Inlet: 40 Nm (29.5 ft lb)
Outlet: 40 Nm (29.5 ft lb)
20 - CONNECTION with Schrader valve
A Schrader valve is installed under the A/C system switches so the switches can be replaced without discharging the A/C system.
- A/C system low and high pressure switches use different size threads.
- Use only the correct switches and 0-ring seals specified for use with R-134a refrigerant and PAG oil.
A - Switch connection (soldered)
B - 0-ring seal
C - Schrader valve insert
HOSES AND LINES
The mixture of refrigerant oil (PAG oil) and refrigerant R-134a attacks some metals and alloys (for example, copper) and breaks down certain hose material. Use only hoses and lines which are identified with a green mark (stripe) or the lettering "R-134a".
Hoses and lines are secured with threaded connections. Always properly torque hose and line connections.
0-RINGS
0-rings seal the connections between components of the A/C system.
Use only new red or green 0-rings which are compatible with R-134a refrigerant and refrigerant (PAG) oil.
Always use correct size 0-rings (dimensions -a- and -b-).
Note
^ Do not reuse 0-rings, always replace.
^ Lubricate 0-rings with refrigerant (PAG) oil before installing.