Air Conditioning (Diagnostics - Introduction): Overview Scion xD I

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1. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED AREA OR NEAR AN OPEN FLAME
2. ALWAYS WEAR EYE PROTECTION
3. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN YOUR EYES OR ON YOUR SKIN If liquid refrigerant gets in your eyes or on your skin: Wash the area with lots of cold water. WARNING: Do not rub your eyes or skin. Apply clean petroleum jelly to the skin. Go immediately to a hospital or see a physician for professional treatment.
4. NEVER HEAT CONTAINER OR EXPOSE THE CONTAINER TO OPEN FLAME
5. BE CAREFUL NOT TO DROP CONTAINER OR APPLY PHYSICAL SHOCKS TO IT
6. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH REFRIGERANT IN REFRIGERANT SYSTEM If there is not enough refrigerant in the A/C system, the oil lubrication will be insufficient and the compressor may be damaged. Necessary care should be taken to avoid this.
7. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE WHILE COMPRESSOR IS OPERATING Open and close only the low pressure valve. If the high pressure valve is opened, refrigerant flows in the reverse direction causing the charging cylinder to rupture.
8. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH REFRIGERANT If the refrigerant is overcharged, it causes problems such as insufficient cooling, poor fuel economy, engine overheating, etc.
9. DO NOT OPERATE ENGINE AND COMPRESSOR WITH NO REFRIGERANT WARNING: Doing so may damage the inside of the compressor because the compressor parts move regardless of whether the A/C system is turned on or off.

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1. GENERAL The air conditioning system has the following controls: Control Outline Variable Capacity Compressor Control Controls the compressor to turn ON or OFF and the discharge capacity based on the signals from various sensors.
2. MODE POSITION AND DAMPER OPERATION Mode Position and Damper Operation FUNCTIONS OF MAIN DAMPERS: Control Damper Operation Position Damper Position Operation Air Inlet Control Damper FRESH A Brings in fresh air. RECIRC B Recirculates internal air. Air Mix Control Damper MAX COLD to MAX HOT Temperature Setting 16°C (61°F) to 30°C (86°F) C, D Continuously changes mix ratio of warm and cool air between COOL and HOT. Mode Control Damper DEF O, R, E, Q Blows air from front defroster and side registers. FOOT / DEF O, K, G, H Blows air from front defroster, side registers, front footwell register, and rear footwell register. FOOT O, K, F, I Blows air from side registers, front footwell register, and rear footwell register. Also, blows some air from front defroster. BI-LEVEL N, R, F, J Blows air from center register, side registers, front footwell register and rear footwell register. FACE M, L, E, J Blows air from center register and side registers.
3. AIR OUTLETS AND AIRFLOW VOLUME Air Outlets and Airflow Volume INDICATION (MODE) CTR SIDE FOOTWELL DEFROSTER A B C D FACE BI-LEVEL FOOT FOOT/DEF DEF The size of the circle o indicates the proportion of airflow volume.
4. A/C COMPRESSOR General The A/C compressor is a continuously variable capacity type in which its capacity varies in accordance with the cooling load of the air conditioner. This compressor consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder, and solenoid control valve. The solenoid control valve adjusts the suction pressure so that the suction pressure can be controlled as desired. A plastic DL (Damper Limiter) type A/C pulley is used. Operation The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (low pressure) and the discharge passage (high pressure). The solenoid control valve operates under duty cycle control in accordance with the signals from the air conditioning amplifier. When the solenoid control valve closes (solenoid coil is energized), a difference in pressure is created and the pressure in the crank chamber decreases. Then, the pressure that is applied to the right side of the piston becomes greater than the pressure that is applied to the left side of the piston. This compresses the spring and tilts the lug plate. As a result, the piston stroke increases and the discharge capacity increases. When the solenoid control valve opens (solenoid coil is not energized), the difference in pressure disappears. Then, the pressure that is applied to the left side of the piston becomes the same as the pressure that is applied to the right side of the piston. Thus, the spring elongates and eliminates the tilt of the lag plate. As a result, there is small piston stroke and the discharge capacity decreases.
5. AMBIENT TEMPERATURE SENSOR The ambient temperature sensor detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the Air Conditioning amplifier.
6. EVAPORATOR TEMPERATURE SENSOR The evaporator temperature sensor detects the temperature of the cool air immediately past the evaporator in the form of resistance changes, and outputs it to the Air Conditioning amplifier.
7. A/C PRESSURE SENSOR The A/C pressure sensor detects the refrigerant pressure and outputs it to the Air Conditioning amplifier in the form of voltage changes.
8. PTC HEATER General The PTC heater is located above the heater core in the air conditioner unit. The PTC heater consists of a PTC element, aluminum fin, and brass plate. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit. PTC Heater Operating Conditions The ON/OFF function of the PTC heater is controlled by the air conditioning amplifier in accordance with the water temperature, ambient temperature, engine speed, air mix setting, and electrical load (generator power ratio). For example, the number of the operating PTC heaters varies by the water temperature as in the graph below.