Air conditioning system SP17
The SP17 is a 173cc fixed displacement swash plate compressor. cm. It consists of five double-ended pistons reciprocating in 10 cylinders under the influence of the swashplate and shaft assembly. There are 10 hemispherical bearing shoes connecting the pistons to the wobble plate and shaft assembly. As the wobble disc rotates, the shoes wobble. In this way, the rotary motion of the wobble plate is converted into a reciprocating motion of the pistons.
System Components - Operation
Compressor
All compressors are driven by a belt from the engine crankshaft through the compressor clutch pulley. The compressor pulley rotates without rotating the compressor shaft until the magnetic clutch solenoid is energized. When the clutch solenoid is energized, the driven plate and clutch hub assembly is pulled back towards the pulley. By the force of an electromagnet, the driven disk of the clutch and the pulley are combined into one unit that rotates the compressor shaft.
When the compressor shaft is driven, the low pressure refrigerant vapor from the evaporator is compressed into high pressure, high temperature vapor. The compressor oil used to lubricate the compressor is carried along with the refrigerant. See «Major overhaul of the air conditioning compressor V5» in this section.
Safety valve
The compressor is equipped with a safety valve installed in the system to ensure safety. Under certain conditions, the pressure of the refrigerant on the outlet side may exceed the calculated operating value. To prevent damage to the system, the valve automatically opens at a pressure of approximately 3171 - 4137 kPa (460 - 600 psi) in the R-134a system. Conditions such as damage to the pressure sensor, failure of the cooling fan, etc., which may cause the valve to open, must be corrected. If necessary, recharge the refrigerant and compressor oil.
Condenser heat exchanger
The condenser assembly, located in front of the radiator, consists of a coil through which the refrigerant flows and cooling fins for fast heat transfer. The air passing through the condenser cools the high pressure refrigerant vapor and causes it to condense into a liquid state.
Expansion valve
The expansion valve can fail in one of three positions: open, closed, or restricting flow.
Expansion valve failing open causes A/C compressor noise or no cooling. The cause could be a broken spring, a broken ball, or excess moisture in the A/C system. If a defective spring or ball is found, the expansion valve must be replaced. If excessive moisture is found in the air conditioning system, the refrigerant must be recharged.
Expansion valve stuck closed causing low suction pressure and no cooling. The cause may be a dome drive failure or excessive moisture in the air conditioning system. If the expansion valve dome drive is found to be defective, the expansion valve must be replaced. If excessive moisture is found in the air conditioning system, the refrigerant must be recharged.
Restriction of flow through the expansion valve causes low suction pressure and no cooling. It can be caused by a clogged refrigeration system. If a blockage is suspected to be the cause, the refrigerant must be recharged, the expansion valve and receiver dryer replaced.
Evaporator core
The evaporator is a device that cools and dehumidifies the air before it enters the car interior. The high pressure liquid refrigerant flows through the opening in the expansion tube and becomes a low pressure gas in the evaporator. The heat of the air passing through the evaporator heat exchanger is transferred to the cooling surface of the heat exchanger, which cools the air. As heat is transferred from the air to the surface of the evaporator heat exchanger, moisture from the air condenses on the outer surface of the evaporator heat exchanger and is discharged to the outside as water.
Receiver dryer
The sealed receiver-drier assembly is connected to the condenser outlet tube. It serves as a refrigerant reservoir, accepting liquid and gaseous refrigerant and compressor oil into the evaporator.
At the bottom of the receiver-dryer is a desiccant that serves to remove moisture that may enter the system.
Heater core
The heater heat exchanger heats the air before it enters the passenger compartment. The engine coolant circulates in the heat exchanger to heat the outside air passing through the heat exchanger fins. The heat exchanger operates continuously and can be used to control the temperature of the conditioned air in air conditioning, heating and ventilation modes.
Control Panel
The air conditioning system is controlled by switches on the control panel. The heating and ventilation panel mounted on the console contains the following elements:
Three rotary knobs
1. Rotary temperature control knob
- The regulator controls the cable.
- Controls the mixing of fresh outside air with heated air inside the vehicle to maintain a customized temperature.
- To increase the temperature of the air entering the passenger compartment, the knob is turned to the right, to the red sector of the regulator.
2. Rotary switch knob
- Driven by an electric motor.
- Controls the distribution of air between the windshield, instrument panel and floor vents.
3. Fan rotary knob
- Turns on the electric fan at one of four speeds.
- In the OFF position, the fan is turned off.
- It works completely independently of the mode switch that controls the heated glass damper and from the temperature control knob.
- Changes the fan speed in all modes and at any position of the temperature controller. However, if the fan rotary knob is in the off position, the air conditioning system is off regardless of the position of the air conditioner switch.
Three keys
1. Air conditioner key
- Controls the air conditioner.
- When the button is pressed, the air conditioner is switched on and the signal lamp lights up. For the air conditioner to work, the rotary fan control must be in one of the four speed settings.
2. Heated rear window button
- Controls the heated rear window.
- Turns on the heated rear window when the button is pressed and the warning light comes on.
3. Ventilation key
- Switches the operating mode between recirculation of air in the passenger compartment and supply of outside air to the passenger compartment.
- Ventilation works in the initial position. The signal lamp lights up when the interior air recirculation is switched on.
- The intake vent flap is driven by an electric motor.
The electric fans of the engine cooling system run constantly when the air conditioner is turned on. This optional feature is part of the A/C control system feature set to prevent excessive compressor temperature rise. In addition, it improves the efficiency of the air conditioning system. The operation of the cooling fans is controlled by the electronic engine management system controller (ECM) through the cooling fan relay.
Pressure meter
The pressure sensor acts as a high and low pressure cut-off switch together with a fan intermittent switch. The pressure sensor is located on the high pressure fluid pipe, behind the right headlight, between the inside of the right front fender and the air filter. The signal from the pressure sensor is sent to the ECM, which controls the operation of the compressor depending on the pressure signal.
Compressor shutdown at wide open throttle (WOT)
When accelerating at full throttle throttle position sensor (TPS) sends a signal to the ECM that controls the compressor clutch.