Air Conditioning
AIR CONDITIONINGThe A/C refrigerant system is a clutch cycling orifice tube-type. The system components are:
- A/C compressor
- A/C clutch assembly
- A/C condenser core
- A/C evaporator core
- Suction accumulator
- Connecting refrigerant lines
The refrigerant system operation is controlled by the:
- A/C evaporator core orifice.
- A/C cycling switch.
- A/C compressor pressure relief valve.
- dual function pressure switch.
The refrigerant system incorporates an A/C compressor controlled by an A/C cycling switch.
The A/C cycling switch senses A/C evaporator core pressure to control A/C compressor operation.
An A/C compressor pressure relief valve is installed in the A/C manifold and tube to protect the refrigerant system against excessively high refrigerant pressures.
An A/C evaporator core orifice is installed in the condenser-to-evaporator tube to meter the liquid refrigerant into the A/C evaporator core.
A/C Compressor Clutch Assembly:
A/C Compressor and Clutch Assembly
NOTE:
- Internal A/C compressor components are not repaired separately. The Visteon FS-10 A/C compressor is repaired only as an assembly. The A/C clutch disc and hub, A/C clutch pulley, A/C clutch field coil and the shaft seal are repairable.
- Installation of a new suction accumulator is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator.
The Visteon FS-10 A/C compressor has the following characteristics:
- A 10-cylinder swashplate design utilizing the tangential design mount
- A 1-piece lip-type seal (installed from the front of the A/C compressor) is used to seal it at the shaft opening in the assembly
- Five double-acting pistons operate within the cylinder assembly. The pistons are actuated by a swashplate that changes the rotating action of the shaft to a reciprocating force
- Reed-type discharge valves are located between the cylinder assembly and the head at each end of the A/C compressor
- The A/C compressor uses PAG oil or equivalent. This oil contains special additives required for the A/C compressor
- The A/C compressor oil from vehicles equipped with a Visteon FS-10 A/C compressor may have a dark color while maintaining a normal oil viscosity. This is normal for this A/C compressor because carbon from the piston rings will discolor the oil
The magnetic A/C clutch has the following characteristics:
- The A/C clutch drives the compressor shaft
- When battery positive voltage (B+) is applied to the A/C clutch field coil, the clutch plate and hub assembly is drawn toward the A/C clutch pulley
- The magnetic force locks the clutch plate and hub assembly and the A/C clutch pulley together as one unit, causing the compressor shaft to rotate
- When B+ is removed from the A/C clutch field coil, springs in the clutch plate and hub assembly move the clutch plate away from the A/C clutch pulley
A/C Compressor Pressure Relief Valve
An A/C compressor pressure relief valve is incorporated in the compressor A/C manifold and tube to:
- relieve unusually high refrigerant system discharge pressure buildups.
- prevent damage to the A/C compressor and other system components.
- avoid total refrigerant loss by closing after the excessive pressure has been relieved.
A/C Condenser Core
NOTE: Installation of a new suction accumulator is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator.
The A/C condenser core has the following characteristics:
- It is an aluminum fin and tube designed heat exchanger located in front of the vehicle radiator
- It cools compressed refrigerant gas by allowing air to pass over fins and tubes to extract heat and by condensing gas to liquid refrigerant as it is cooled
A/C Evaporator Core
NOTE:
- The evaporator core is not separately serviceable, it is serviced only with the evaporator core housing assembly.
- Installation of a new suction accumulator is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator.
The A/C evaporator core is an aluminum plate/fin-type.
- A mixture of refrigerant and oil enters the bottom of the A/C evaporator core through the A/C evaporator core inlet tube and then moves out of the A/C evaporator core through the A/C evaporator core outlet tube.
- The evaporator core is located in front of the instrument panel in the heater core and evaporator core housing.
A/C Evaporator Core Orifice
The A/C evaporator core orifice has the following characteristics:
- It is located in the rear condenser-to-evaporator tube and can be removed through an access fitting
- It has filter screens located on the inlet and outlet ends of the tube body
- The inlet filter screen acts as a strainer for the liquid refrigerant flowing through the A/C evaporator core orifice
- O-ring seals on the A/C evaporator core orifice prevent the high-pressure liquid refrigerant from bypassing the A/C evaporator core orifice
- Adjustment or repair cannot be made to the A/C evaporator core orifice assembly. It must be serviced as a unit
Suction Accumulator
NOTE: Installation of a new suction accumulator is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator.
The suction accumulator is mounted behind the RH corner of the front bumper cover, in front of the RH front wheel well. The inlet tube of the suction accumulator is attached to the evaporator outlet line. The outlet tube attaches to the A/C manifold and tube.
After entering the inlet of the suction accumulator, heavier oil-laden refrigerant contacts an internally mounted dome (which serves as an umbrella) and drips down onto the bottom of the canister.
- A small diameter oil bleed hole, in the bottom of the vapor return tube, allows the accumulated heavier liquid refrigerant and oil mixture to reenter the compressor suction line at a controlled rate.
- As the heavier mixture passes through the small diameter liquid bleed hole, it has a second chance to vaporize and recirculate through the A/C compressor without causing compressor damage due to slugging.
- A fine mesh screened filter fits tightly around the bottom of the vapor return tube to filter out refrigerant system contaminant particles.
- A desiccant bag is mounted inside the canister to absorb any moisture which may be in the refrigerant system.
A/C Cycling Switch
The A/C cycling switch is mounted on a Schrader-type valve fitting on the evaporator outlet line.
- A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.
- This allows the suction pressure inside the evaporator outlet line to control the operation of the A/C cycling switch.
- The electrical switch contacts open when the suction pressure drops. The contacts close when the suction pressure rises.
- The A/C cycling switch will control the A/C evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.
- This prevents icing of the A/C evaporator core and blockage of air flow.
- It is not necessary to discharge the refrigerant system to remove the A/C cycling switch.
Dual Function Pressure Switch
The dual function pressure switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.
- The dual function pressure switch is mounted on a Schrader-type valve fitting on the condenser-to-evaporator tube.
- A valve depressor, located inside the threaded end of the dual function pressure switch, presses on the Schrader valve stem.
- This allows the dual function pressure switch to monitor the compressor discharge pressure.
- It is not necessary to recover the refrigerant to remove the dual function pressure switch.
- The dual function pressure switch has 2 sets of contacts. One electrical contact is normally closed.
- When the compressor discharge pressure rises, the switch contacts open, interrupting the 12 volt A/C request (ACCS) signal to the PCM and disengaging the A/C compressor. When the pressure drops, the contacts close, completing the 12 volt A/C request (ACCS) signal to the PCM and enabling the A/C compressor.
The switch contains a second set of electrical contacts used for high-speed fan control.
- When the compressor discharge pressure rises, the contacts close and send a 12 volt signal (ACPSW) to the PCM requesting high speed cooling fan operation. When the pressure drops, the contacts open and the 12 volt signal is interrupted.
Service Gauge Port Valves:
The fitting is an integral part of the refrigeration line or component.
- Special couplings are required for both the high side and low side service gauge ports.
- The Schrader-type valve core can be serviced if the seal leaks.
- Always install the A/C charging valve cap on the service gauge port valves after repairing the refrigerant system.