Auxiliary Climate Control: Overview Ford Explorer V

Overview

1. Always wear safety goggles.
2. Avoid contact with liquid refrigerant R-134a. R-134a vaporizes at approximately -25 C (-13 F) under atmospheric pressure and will freeze skin tissue.
3. Never allow refrigerant R-134a gas to escape in quantity in an occupied space. It will displace the oxygen needed to support life.
4. 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.

Failure to follow these instructions may result in serious personal injury.

Note. To avoid damaging the vehicle or A/C components, the following precautions must be observed.

1. 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.
2. 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.
3. 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.
4. 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 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.
5. 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.
6. 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.

Note. To avoid contamination of the A/C system, the following precautions must be observed.

1. Never open or loosen a connection before recovering the refrigerant.
2. When loosening a connection, if any residual pressure is evident, allow it to leak out before opening the fitting.
3. Evacuate a system that has been opened to install a new component or one that has discharged through leakage before charging.
4. Seal open fittings with a cap or plug immediately after disconnecting a component from the system.
5. Clean the outside of the fittings thoroughly before disconnecting a component from the system.
6. Do not remove the sealing caps from a new component until ready to install.
7. 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.
8. Install a new O-ring seal before connecting an open fitting. Coat the fitting and O-ring seal with PAG oil before connecting.
9. When installing a refrigerant line, avoid sharp bends. Position the line away from the exhaust or any sharp edges that can chafe the line.
10. Tighten threaded fittings only to specifications. The steel and aluminum fittings used in the refrigerant system will not tolerate overtightening.
11. When disconnecting a fitting, use a wrench on both halves of the fitting to prevent twisting of the refrigerant lines or tubes.
12. 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.

An auxiliary climate control system is available as optional equipment. The auxiliary climate control system operation is determined by the settings on the front or rear auxiliary climate control assembly. The auxiliary climate control assemblies include a blower motor switch and temperature control/air distribution mode knob, neither of which can be individually serviced.

Auxiliary blower motor operation is enabled when the HVAC system is in any mode except OFF. The auxiliary system air can be cooled below interior air temperature only when A/C compressor operation has been requested by the settings of the climate control assembly of the base (front) system. The auxiliary system air can be heated at any time.

Scheme 3

Normal Operation and Fault Conditions

The auxiliary blower motor relay coil receives a ground from the HVAC module. When the relay coil is energized, voltage is delivered from the relay to the auxiliary blower motor speed control and auxiliary blower motor. The auxiliary blower motor speed control is grounded. The HVAC module provides a PWM signal to the auxiliary blower motor speed control to control the blower speed. Ground for the motor is provided from the auxiliary blower motor speed control.

DTC FAULT TRIGGER CONDITIONS

The auxiliary blower motor relay coil receives a ground from the HVAC module. When the relay coil is energized, voltage is delivered from the relay to the auxiliary blower motor speed control and auxiliary blower motor. The auxiliary blower motor speed control is grounded. The HVAC module provides a PWM signal to the auxiliary blower motor speed control to control the blower speed. Ground for the motor is provided from the auxiliary blower motor speed control.

DTC FAULT TRIGGER CONDITIONS

To rotate the auxiliary temperature blend door actuator, the HVAC module supplies voltage and ground to the auxiliary temperature blend door actuator motor through the actuator motor circuits. To reverse the auxiliary temperature blend door actuator rotation, the HVAC module reverses the voltage and ground circuits.

The auxiliary temperature blend door actuator feedback resistor is supplied a 5-volt reference voltage and ground from the HVAC module. The HVAC module measures the resistance on the auxiliary temperature blend door actuator feedback circuit to determine the auxiliary temperature blend door actuator position by the position of the actuator feedback resistor wiper arm.

During an actuator calibration cycle, the HVAC module drives the auxiliary temperature blend door until the door reaches both internal stops in the HVAC case. If the auxiliary temperature blend door is temporarily obstructed or binding during a calibration cycle, the HVAC module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC module commands the actuator to its end of travel, the airflow may not be from the expected outlets.

DTC FAULT TRIGGER CONDITIONS

To rotate the auxiliary mode door actuator, the HVAC module supplies voltage and ground to the auxiliary mode door actuator motor through the actuator motor circuits. To reverse the auxiliary mode door actuator rotation, the HVAC module reverses the voltage and ground circuits.

The auxiliary mode door actuator feedback resistor is supplied a 5-volt reference voltage and ground from the HVAC module. The HVAC module measures the resistance on the auxiliary mode door actuator feedback circuit to determine the auxiliary mode door actuator position by the position of the actuator feedback resistor wiper arm.

During an actuator calibration cycle, the HVAC module drives the auxiliary mode door until the door reaches both internal stops in the HVAC case. If the auxiliary mode door is temporarily obstructed or binding during a calibration cycle, the HVAC module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC module commands the actuator to its end of travel, the airflow may not be from the expected outlets.

DTC FAULT TRIGGER CONDITIONS

Under normal operation, the rear auxiliary control is supplied a 5-volt reference and ground from the HVAC module. When the auxiliary blower motor speed, airflow mode or temperature control is adjusted, the HVAC module reads the voltage from the rear auxiliary climate controls on the auxiliary blower motor speed, airflow mode and temperature control feedback circuits to determine the requested setting.

DTC FAULT TRIGGER CONDITIONS

The purpose of this pinpoint test is to test the functions of the HVAC system and to identify the correct pinpoint test HVAC symptom.