Air Conditioning
AIR CONDITIONINGThe A/C refrigerant system is a clutch cycling orifice tube type. The system components are:
- A/C compressor.
- A/C condenser core.
- A/C evaporator core.
- suction accumulator.
- connecting refrigerant lines.
The refrigeration system operation is controlled by the:
- evaporator core orifice tube.
- A/C cycling switch.
- A/C compressor pressure relief valve.
- A/C high-pressure cutoff switch.
The refrigerant system incorporates an A/C compressor controlled by the powertrain control module (PCM) through an A/C clutch relay.
The A/C cycling switch senses evaporator core pressure to control A/C compressor operation.
An evaporator core orifice tube is installed in the condenser-to-evaporator line to meter the liquid refrigerant into the evaporator core.
The A/C compressor clutch will only be engaged by the PCM if all of the following conditions are met:
- The climate control assembly is set to a mode which provides an A/C request to the PCM.
- The A/C cycling switch is reading an acceptable evaporator core pressure.
- The A/C high-pressure cutoff switch is not open due to excessive pressure in the high side of the refrigerant system.
- The A/C compressor relay is switched to the closed position by the PCM.
- The engine coolant temperature is not excessively high.
- The PCM has not detected a wide open throttle (WOT) condition.
An A/C compressor pressure relief valve is installed in the compressor manifold and tube assembly to protect the refrigerant system against excessively high refrigerant pressures.
A/C Compressor and Clutch Assembly
NOTE:
- Internal A/C compressor components are not serviced separately. The SC115 A/C compressor is serviced only as an assembly. The clutch plate, clutch pulley and bearing, and the clutch field coil are serviceable.
- 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.
- Vehicles equipped with fixed scroll A/C compressors may experience rapid refrigerant high side pressure fluctuations upon cold startups and/or after refrigerant system recharges. These high side refrigerant fluctuations are characteristic of the fixed scroll compressor and not an indication of a failing/failed A/C compressor.
The SC115 A/C compressor has the following characteristics:
- Tangential-mount design - 3 lugs.
- The single manifold block of the compressor manifold and tube assembly fits to the suction and discharge ports. Two O-ring seals are used for sealing.
- An eccentric bushing is driven by the shaft of the A/C compressor.
- An orbiting scroll driven by the eccentric bushing compresses the refrigerant gas against the walls of the fixed scroll.
- A single reed-type discharge valve mounted on the back of the fixed scroll. There are no suction valves.
- A non-serviceable shaft seal fully supported on both sides by bearings.
- 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 an SC115 A/C compressor may have some slightly dark-colored streaks while maintaining normal oil viscosity. This is normal for this A/C compressor because of break-in wear of the scroll seals that can discolor the oil.
- Use standard oil matching procedures when installing new compressors.
The magnetic A/C clutch has the following characteristics:
- It drives the compressor shaft.
- When battery voltage is applied to the A/C compressor 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 battery voltage is removed from the A/C compressor 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 manifold and tube assembly 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.
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 condenser core has the following characteristics:
- It is an aluminum fin and tube design 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.
Refrigerant Lines
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 compressor manifold and tube assembly is attached to the A/C compressor, is sealed with O-ring seals and has the following features:
- The upstream side contains low-pressure refrigerant gas.
- The downstream side contains high-pressure refrigerant gas and a fitting used to mount a serviceable high-pressure A/C charge port valve.
- The downstream side also contains a fitting used to mount the A/C high-pressure cutoff switch. A long-travel Schrader-type valve stem core is installed in the fitting so that the A/C high-pressure cutoff switch can be removed without discharging the A/C system.
Evaporator Core
NOTE:
- The evaporator core is not separately serviceable, it is serviced only with the evaporator core housing assembly.
- If an evaporator core leak is suspected, the evaporator core must be vacuum leak tested before it is removed from the vehicle.
- 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 evaporator core is the plate/fin type with a unique refrigerant flow path.
- A mixture of refrigerant and oil enters the bottom of the evaporator core through the evaporator core inlet tube, continues over to the remaining 5 plate/fin sections, and then moves out of the evaporator core through the evaporator core outlet tube.
- This W-pass flow pattern accelerates the flow of refrigerant and oil through the evaporator core.
Evaporator Core Orifice Tube
NOTE: A new evaporator core orifice tube should be installed whenever a new A/C compressor is installed.
The A/C evaporator core orifice has the following characteristics:
- It is color-coded red.
- It is located in the condenser to evaporator line.
- 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 evaporator core orifice tube.
- O-ring seals on the evaporator core orifice tube prevent the high-pressure liquid refrigerant from bypassing the evaporator core orifice tube.
- It can be accessed through a fitting located near the middle of the condenser-to-evaporator line.
- Adjustment or service cannot be carried out to the evaporator core orifice tube. A new evaporator core orifice must be installed.
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 to the right of the radiator support. The evaporator outlet line attaches directly to the inlet of the suction accumulator and the compressor manifold and tube assembly attaches to the suction accumulator outlet.
After entering the inlet of the suction accumulator, the 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 re-enter 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 inlet 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.
Air Conditioning (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.
- When the A/C cycling switch contacts close, the signal to energize the A/C compressor clutch filed coil is sent to the A/C control relay.
- When the A/C cycling switch contacts open, the A/C compressor clutch field coil is de-energized and A/C compressor operation stops.
- The A/C cycling switch will control the evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.
- This prevents icing of the evaporator core and blockage of airflow.
- It is not necessary to discharge the refrigerant system to remove the A/C cycling switch.
High-Pressure Cutoff Switch
The high-pressure cutoff switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.
- The high-pressure cutoff switch is mounted on a Schrader-type valve fitting on the high pressure side of the compressor manifold and tube assembly.
- A valve depressor, located inside the threaded end of the high-pressure cutoff switch, presses on the Schrader valve stem.
- This allows the high-pressure cutoff switch to monitor the A/C compressor discharge pressure.
- When the A/C compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the pressure drops, the contacts close to allow operation of the A/C compressor.
- It is not necessary to discharge the refrigerant system to remove the high-pressure cutoff switch.
Spring Lock Coupling:
Spring Lock Coupling
The spring lock coupling is a refrigerant line coupling held together by a garter spring inside a circular cage.
- When the coupling is connected together, the flared end of the female fitting slips behind the garter spring inside the cage of the male fitting.
- The garter spring and cage then prevent the flared end of the female fitting from pulling out of the cage.
- Three O-ring seals are used to seal between the 2 halves of the couplings.
- Use only the O-ring seals listed in the Ford Master Parts Catalog for the spring lock coupling.
- A plastic indicator ring is used on the spring lock couplings of the evaporator core to indicate, during vehicle assembly, that the coupling is connected. Once the coupling is connected, the indicator ring is no longer necessary but will remain captive by the coupling near the cage opening.
- The indicator ring may also be used during service operations to indicate connection of the coupling.
- An A/C tube lock coupling clip may be used to secure the coupling but is not required.
Peanut Fitting
The condenser core uses peanut-shaped refrigerant fittings instead of spring lock couplings.
- The male and female blocks of the peanut fitting are retained with a nut.
- An O-ring seal is installed around the tube on the male block.
- Support the female fitting with a wrench to prevent twisting of the tubes.
- When correctly assembled the male and female fittings should be flush.
Refrigerant System Dye
Fluorescent refrigerant system dye is added to the refrigerant system at the factory to assist in refrigerant system leak diagnosis using a Rotunda-approved ultraviolet blacklight. It is not necessary to add additional dye to the refrigerant system before diagnosing leaks, even if a significant amount of refrigerant has been removed from the system. Replacement suction accumulators are shipped with a fluorescent dye "wafer" included in the desiccant bag which will dissolve after approximately 30 minutes of continued A/C operation. It is not necessary to add dye after flushing or filtering the refrigerant system because a new suction accumulator is installed as part of the flushing or filtering procedure. Additional refrigerant system dye should only be added if more than 50% of the refrigerant system lubricant capacity has been lost due to a fitting separation, hose rupture or other damage.