GENERAL DESCRIPTION
When servicing the compressor, keep dirt or foreign material from getting on or into the compressor parts and system. Clean tools and a clean work area are important for proper service. The compressor connections and the outside of the compressor should be cleaned before any "On-Vehicle" repair, or before removal of the compressor. The parts must be kept clean at all times and any parts to be reassembled should be cleaned with Trichloroethane, naphtha, kerosene, or equivalent solvent, and dried with dry air. Use only lint free cloths to wipe parts.
The operations described below are based on bench overhaul with compressor removed from the vehicle, except as noted. They have been prepared in order of accessibility of the components. When the compressor is removed from the vehicle for servicing, the oil remaining in the compressor should be discarded and new compressor oil added to the compressor.
Compressor malfunction will appear in one of four ways: noise, seizure, leakage or low discharge pressure. Resonant compressor noises are not cause for alarm; however, irregular noise or rattles may indicate broken parts or excessive clearances due to wear. To check seizure, de-energize the magnetic clutch and check to see if the drive plate can be rotated. If rotation is impossible, the compressor is seized. Low discharge pressure may be due to a faulty internal seal of the compressor, or a restriction in the compressor. Low discharge pressure may also be due to an insufficient refrigerant charge or a restriction elsewhere in the system. These possibilities should be checked prior to servicing the compressor. If the compressor is inoperative, but is not seized, check to see if current is being supplied to the magnetic clutch coil terminals.
The compressor oil used in the HFC-134a system compressor differs from that used in R-12 systems.
Also, compressor oil to be used varies according to the compressor model. Be sure to avoid mixing two or more different types of oil.
If the wrong oil is used, lubrication will be poor and the compressor will seize or malfunction.
OIL RETURN OPERATION
There is close affinity between the oil and the refrigerant. During normal operation, part of the oil recirculates with the refrigerant in the system. When checking the amount of oil in the system, or replacing any component of the system, the compressor must be run in advance for oil return operation. The procedure is as follows
- Open all the doors and the engine hood.
- Start the engine and air conditioning switch to "ON" and set the fan control knob at its highest position.
- Run the compressor for more than 20 minutes between 800 and 1,000 RPM in order to operate the system.
- Stop the engine.
Using a variety of sensors, this automatic air conditioner accurately senses outside air temperature, solar radiation quantity, evaporator's blowing temperature, and interior temperature, then enters these data to the automatic air conditioner control unit (equipped with the built-in micro-computer). The data provided to the control unit enables to automatically control blow temperature and blow air quantity, turn on or off the compressor and switch the blow port as well as switching between the fresh air intake and interior air circulation.
Resetting the automatic function allows you to switch to the manual control mode.
The self-diagnoisis function of the automatic air conditioner control unit (with the built-in micro-computer) allows the unit to access and diagnose a failed part easier and quicker.
Scheme 4
OVERVIEW OF AUTOMATIC CONTROL OF AUTOMATIC AIR CONDITIONER
The automatic air conditioner on this vehicle has the following features
- Interior temperature control.
- Air flow control.
- Mode (blow port) control.
- Intake (switching between fresh air and interior air) control.
- Heater start timing control.
- Cooler start timing control.
- Evaporator anti-freeze control.
SYSTEM OVERVIEW (CHART)
Conditions both inside and outside the vehicle are detected by sensors (in-car temperature sensor, ambient temperature sensor, duct sensor, sun sensor, speed sensor, and water temperature sensor). These sensors send signals to the control unit.
Potentiometer position sensors send data to the control unit. Signals related to control panel settings are also sent to the control unit.
In response to the signals received, the control unit automatically adjusts air-mix door aperture (outlet air temperature), fan speed (forced air volume), and air intake (outside air, recirculated inside air, or a mixture of the two).
Scheme 5
Mode switch operation
Press the mode switch to change to the outlet mode. Blower operation (outlet mode position) can now be switched between the VENT, BI-LEVEL, FOOT, and DEF positions.
Defroster switch operation
The DEF position can be selected from the outlet mode.
Scheme 6
TROUBLESHOOTING, ITS OVERVIEW AND PROCEDURES
The automatic air conditioner is equipped with the "Self-Diagnosis Function" to check its major components.
This function makes access to the sensors, actuators and blower fan motor system easier when checking them up and, when a failed part is located, this function restores its original performance.
When implementing the troubleshooting, this self-diagnosis function narrows the range to be searched at the first step, then check relevant parts one by one according to the "Checking Procedures by Failed Location". As for a location this function is unappreciable, the system accurately determines characteristics of a given trouble and checks relevant parts according to the "Checking Procedures by Failed Location".
The following illustrates basic troubleshooting flow.
Scheme 7
OVERVIEW OF SELF-DIAGNOSIS FUNCTION
Sensors (input) and actuators (output) are used to check circuit function and provide essential data on these circuits. For more detailed information, refer to the INSPECTION AND REPAIR sections for the applicable system or component.
The Table below shows how to turn the self-diagnosis function on and off.
