In the Renault Logan, the interior heating and ventilation system is controlled independently from the air conditioning system for heating and ventilation, removing frost and condensation from the windshield, and defrost of the door windows.
At the same time, the main heating elements also operate when the air conditioning is on.
The heater components and the air conditioning evaporator heat exchanger are integrated into a single unit.
Main components of the heater:
- - heater heat exchanger (radiator), designed to heat the air entering the passenger compartment with the heat of the engine coolant;
- - electrically driven fan (blower), providing a regulated supply of outside air to the heater and air conditioner flaps;
- - flap that regulates the temperature of the air coming from the heater into the passenger compartment; changing its position determines the amount of air passing through the heater heat exchanger and outside air bypassing the heat exchanger;
- - flaps that distribute air coming from the heater through the air ducts into the passenger compartment or for defroster of the windshield.
The air conditioning system includes the following Elements
Compressor
The compressor is belt-driven from the engine crankshaft pulley.
The compressor pulley has a built-in electromagnetic friction clutch that disconnects the compressor shaft from the pulley or connects them when the air conditioner is running, based on a signal from the engine control unit.
During operation, the compressor compresses the refrigerant vapor entering it from the evaporator heat exchanger to high pressure.
The temperature of the refrigerant vapor at the compressor outlet is significantly higher than at the inlet.
The pressure-reducing valve is built into the compressor and performs a protective function, triggering when the pressure at the compressor outlet increases above the permissible value.
The pressure-reducing valve may be triggered by a failure of the high-pressure valve, electric fan, or etc.
The condenser heat exchanger (radiator) is located behind the engine cooling system radiator and has a coil with developed fins for rapid cooling and condensation of refrigerant vapors compressed by the compressor to high pressure.
A throttle valve (reducer) with mesh filters at the inlet and outlet is installed in the pipeline supplying liquid refrigerant to the evaporator heat exchanger.
The throttle valve in the valve limits the flow of liquid refrigerant and reduces the pressure in the evaporator.
After the engine stops, liquid refrigerant continues to flow through the throttle valve for some time from the high-pressure area to the low-pressure area.
Liquid flowing through the throttle valve is accompanied by a characteristic hissing sound, which can be heard for 30-60 seconds after the engine stops and does not indicate a malfunction.
Evaporator heat exchanger (radiator)
Liquid refrigerant from the condenser heat exchanger flows through the throttle valve The cuttings enter the evaporator heat exchanger, located in the heater unit.
In the heat exchanger, the liquid transforms into a gaseous state, absorbing heat. Moisture contained in the air entering the heat exchanger condenses on it, drains from the evaporator, and is removed from the heater unit.
From the evaporator heat exchanger, the gaseous refrigerant, mixed with a small amount of liquid refrigerant and droplets of refrigeration oil, enters the receiver, which is connected to the evaporator outlet pipe.
Receiver-dryer
The lower part of the receiver housing contains a container with an absorber for water vapor from the refrigerant vapor. The vapor, released from moisture through a special opening in the intake tube, mixes with the refrigeration oil.
The upper part of the receiver housing contains fittings for connecting the pipes.
The receiver is not repairable; it must be replaced only as an assembly.
In addition to the listed elements, the system includes High and low pressure valves and pressure sensors.
A basic diagram of refrigerant flow in an air conditioning system is shown in Figure 2.
All air conditioning system repair work should only be performed with the system completely discharged.
Since refrigerant vapors are toxic, repair the system using specialized equipment available at specialized air conditioning service centers.