Ford Focus Service Manual: Climate Control System - General Information and Diagnostics

Climate Control System Operation

WARNING: Take the following
precautions when repairing an air conditioning system containing R-134a:

• Always wear safety goggles.
• Avoid contact with liquid refrigerant R-134a. R-134a vaporizes at approximately -25°C (-13°F) under atmospheric pressure and will freeze skin tissue.
• Never allow refrigerant R-134a gas to escape in quantity in an occupied space. It will displace the oxygen needed to support life.
• Never use a torch in an atmosphere containing R-134a gas. R-134a is non-toxic at all normal conditions, but it decomposes when exposed to high temperatures such as a torch flame. During decomposition it releases irritating and toxic gasses (as described in the MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid, carbon dioxide and water.

NOTICE: To avoid damaging the vehicle or Air Conditioning (A/C) components, the following precautions must be observed.

• The A/C refrigerant of all vehicles must be identified and analyzed prior to refrigerant charging. Failure to do so can contaminate the shop bulk refrigerant and other vehicles.
• Do not add R-12 refrigerant to an A/C system that requires the use of R-134a refrigerant. These 2 types of refrigerant must never be mixed. Doing so can damage the A/C system.
• Charge the A/C system with R-134a refrigerant gas while the engine is running only at the low-pressure side to prevent refrigerant slugging from damaging the A/C compressor.
• Use only R-134a refrigerant. Due to environmental concerns, when the A/C system is drained, the refrigerant must be collected using refrigerant recovery/recycling equipment. Federal, State/Provincial and/or local laws REQUIRE that R-134a be recovered into appropriate recovery equipment and the process be conducted by qualified technicians who have been certified by an approved organization, such as ASE or Mobile Air Conditioning Society (MACS) . Use of a recovery machine dedicated to R-134a is necessary to reduce the possibility of oil and refrigerant incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the A/C system.
• Refrigerant R-134a must not be mixed with air for leak testing or used with air for any other purpose above atmospheric pressure. R-134a is combustible when mixed with high concentrations of air and higher pressures.
• A number of manufacturers are producing refrigerant products that are described as direct substitutes for refrigerant R-134a. The use of any unauthorized substitute refrigerant can severely damage the A/C components. If repair is required, use only new or recycled refrigerant R-134a.

NOTICE: To avoid contamination of the Air Conditioning (A/C) system, the following precautions must be observed.

• Never open or loosen a connection before recovering the refrigerant.
• When loosening a connection, if any residual pressure is evident, allow it to leak out before opening the fitting.
• Evacuate a system that has been opened to install a new component or one that has discharged through leakage before charging.
• Seal open fittings with a cap or plug immediately after disconnecting a component from the system.
• Clean the outside of the fittings thoroughly before disconnecting a component from the system.
• Do not remove the sealing caps from a new component until ready to install.
• Refrigerant oil will absorb moisture from the atmosphere if left uncapped. Do not open an oil container until ready to use and install the cap immediately after using. Store the oil in a clean, moisture-free container.
• Install a new O-ring seal before connecting an open fitting. Coat the fitting and O-ring seal with PAG oil before connecting.
• When installing a refrigerant line, avoid sharp bends. Position the line away from the exhaust or any sharp edges that can chafe the line.
• Tighten threaded fittings only to specifications. The steel and aluminum fittings used in the refrigerant system will not tolerate overtightening.
• When disconnecting a fitting, use a wrench on both halves of the fitting to prevent twisting of the refrigerant lines or tubes.
• Do not open a refrigerant system or uncap a new component unless it is as close as possible to room temperature. This will prevent condensation from forming inside a component that is cooler than the surrounding air.

The system consists of the following components:

• A/C compressor
• A/C compressor clutch assembly
• A/C condenser core
• A/C evaporator core
• Receiver/drier
• Connecting refrigerant lines
• Thermostatic Expansion Valve (TXV)
• Heater core and evaporator core housing
• HVAC module
• Blower switch
• Temperature blend door actuator
• Floor/defrost/panel door actuator
• Air inlet door actuator
• Blower motor resistor or speed control module
• Blower motor
• Evaporator discharge air temperature sensor

HVAC System

The HVAC system heats or cools the vehicle depending on the HVAC control panel selection.

• The HVAC control panel selections determine heating or cooling, air distribution and enables blower motor operation.
• The temperature control setting determines the air temperature.
• The blower motor switch varies the blower motor speed.
• During A/C operation the system also reduces the relative humidity of the air.

The HVAC system operation is determined by the settings on the climate control module. The HVAC system is composed of the HVAC module, blower motor resistor, mode door actuator, air inlet door actuator and temperature blend door actuator to control the various functions.

The blower motor switch:

• sets the blower motor speed.
• directs the blower motor path to ground through the blower motor resistor to allow blower motor operation in LO, MED-LO and MED-HI.
• directs the blower motor path directly to ground, bypassing the blower motor resistor, to allow blower motor operation in HI.

The A/C request button:

• can request the A/C compressor ON or OFF when the function selector switch is in PANEL, FLOOR/PANEL, FLOOR/DEFROST and FLOOR as the A/C request switch is pressed. Indicator illuminates when A/C request switch is toggled ON.
• is inoperative in MAX A/C and OFF.
• indicator illuminates when the function selector switch is in MAX A/C and cannot be toggled OFF.
• indicator does not illuminate in OFF and cannot be toggled ON.
• indicator can be toggled ON or OFF in FLOOR/DEFROST and DEFROST modes. However, the A/C compressor request can operate regardless of indicator status, in these modes, if the outside air temperature is above 6°C (43°F).
• is serviced only with the HVAC module.

The function selector:

• selects airflow direction.
• is serviced only with the HVAC module.

The temperature selector:

• controls the temperature blend door actuator and door, allowing adjustment of outlet temperatures.

The air recirculation button:

• selects either recirculated or outside air source.
• recirculates air in any mode except DEFROST, if requested.
• is disabled in MAX A/C or OFF mode where recirculated air only is used.
• is disabled in DEFROST mode where outside air only is used.
• may automatically turn off in FLOOR/DEFROST and DEFROST modes after 5 minutes.
• is serviced only with the HVAC module.

The HVAC module also includes:

• a rear window defrost button, refer to Section  501-11.

External Temperature Display

While the actual external temperature can vary continuously, the value that is displayed will update at a specific rate depending on whether or not the engine is "hot" and whether or not the vehicle is moving.

When the external temperature is rising, the display will update slowly.

Updates (when the actual external temperature is higher than currently displayed value) will be limited to 0.6°C (1°F) every 20 seconds while the vehicle is moving at greater than 40 km/h (25 mph) for more than 90 seconds or 0.6°C (1°F) every 20 minutes if the vehicle is not moving at this speed. This is to prevent the heat from the engine compartment from affecting the accuracy of the display.

When the external temperature is dropping, the display will update quickly.

Updates (when the actual external temperature is lower than currently displayed value) will only be limited to 0.6°C (1°F) every 2 seconds (regardless of vehicle speed). Consequently the display will essentially follow the drop experienced by the external temperature thermistor.

System Airflow Description

Max A/C

When MAX A/C is selected:

• the air inlet door actuator closes off outside air and admits only recirculated air.
• the recirc button is disabled and the indicator is illuminated.
• the floor/defrost/panel door directs airflow to the instrument panel A/C registers.
• blended air temperature is available.
• the A/C request button is illuminated and will be disabled.
• the A/C compressor can operate if the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.

PANEL

When PANEL is selected:

• the recirc request button is enabled. If the recirc request button is selected (indicator ON), the air inlet door actuator closes off outside air from entering the passenger compartment. If the recirc request button is not selected (indicator OFF), the air inlet door actuator admits only outside air into the passenger compartment.
• the floor/defrost/panel door directs airflow to the instrument panel A/C registers.
• blended air temperature is available.
• the A/C request button is enabled. The A/C compressor can operate and the indicator will illuminate if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.

PANEL/FLOOR

When PANEL/FLOOR is selected:

• the recirc request button is enabled. If the recirc request button is selected (indicator ON), the air inlet door actuator closes off outside air from entering the passenger compartment. If the recirc request button is not selected (indicator OFF), the air inlet door actuator admits only outside air into the passenger compartment.
• the floor/defrost/panel door directs airflow to the floor duct and the instrument panel A/C registers. A small amount of airflow from the side window demisters and defrost duct will be present.
• blended air temperature is available.
• the A/C request button is enabled. The A/C compressor can operate and the indicator will illuminate if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.

OFF

When OFF is selected:

• the recirc request button is disabled.
• the air inlet door actuator closes off outside air and admits only recirculated air. This is done to prevent the natural flow of air through the outlets during vehicle movement.
• the A/C request button is disabled.
• the blower motor is OFF.

FLOOR

When FLOOR is selected:

• the recirc request button is enabled. If the recirc request button is selected (indicator ON), the air inlet door actuator closes off outside air from entering the passenger compartment. If the recirc request button is not selected (indicator OFF), the air inlet door actuator admits only outside air into the passenger compartment.
• the floor/defrost/panel door directs airflow to the floor duct. A small amount of airflow from the defroster duct and side window demisters will be present.
• blended air temperature is available.
• the A/C request button is enabled. The A/C compressor can operate and the indicator will illuminate if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.

FLOOR/DEFROST

When the FLOOR/DEFROST is selected:

• the recirc request button is enabled. If the recirc request button is selected (indicator ON), the air inlet door actuator closes off outside air from entering the passenger compartment. If the recirc request button is not selected (indicator OFF), the air inlet door actuator admits only outside air into the passenger compartment.
• the floor/defrost/panel door directs airflow to the floor duct, the defroster duct and the side window demisters.
• blended air temperature is available.
• the A/C request button and indicator can be toggled. To reduce fogging, the A/C compressor request will operate automatically, regardless of indicator status, if the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.

DEFROST

When DEFROST is selected:

• the air inlet door actuator opens, admitting only outside air into the passenger compartment.
• the floor/defrost/panel door directs airflow to the defroster duct and side window demisters. A small amount of airflow from the floor duct will be present.
• blended air temperature is available.
• the A/C request button and indicator can be toggled. To reduce fogging, the A/C compressor request will operate automatically, regardless of indicator status, if the outside temperature is above approximately 6°C (43°F).
• the blower motor is ON.