Refrigerant Circuit Components
Refrigerant Circuit Components
CAUTION:
- Unapproved tools or materials (such as leak sealing additives) can cause damage or malfunctions in the system.
- Only use tools and materials approved by the manufacturer.
- The warranty is voided if unapproved tools or materials are used.
- All components of the refrigerant circuit submitted for quality observation are always to be sealed (use original sealing caps of original part).
- Replace damaged or leaking components of refrigerant circuit.
- To date, the original parts (compressor, reservoir, receiver, evaporator and condenser) have been filled with nitrogen gas. This charge is being gradually discontinued. Little or no pressure equalization is therefore noticeable on unscrewing sealing plugs from original parts.
Refrigerant Circuit Component Arrangement
High pressure side are the condenser, receiver and restrictor or expansion valve to separate the high and low pressure liquid ends.
High pressure results from the restrictor or expansion valve forming a constriction and causing the refrigerant to accumulate, thus leading to an increase in pressure and temperature.
Excess pressure occurs if too much refrigerant or refrigerant oil is used, the condenser is contaminated, the radiator fan is malfunctioning, the system is blocked or in the event of moisture in the refrigerant circuit (icing-up of restrictor or expansion valve).
Low pressure side are the evaporator, reservoir, evaporator temperature sensor and compressor to separate high and low pressure gas ends.
A drop in system pressure can occur due to loss of refrigerant, restrictor or expansion valve (restriction not given), A/C compressor malfunction or iced evaporator.
A/C Compressor with Magnetic Clutch
A/C compressor is driven by vehicle engine via a ribbed belt.
An electromagnetic clutch installed on the A/C compressor creates a frictional connection between the ribbed belt pulley and A/C compressor crankshaft when the air conditioning system is switched on.
If the A/C compressor sticks, a fuse installed in the compressor ribbed belt pulley releases the electromagnetic clutch and protects the ribbed belt pulley from overload.
The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and relays it to the condenser.
NOTE:
- The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature.
- The refrigerant for which the A/C compressor is designed is listed on the manufacturers plate. A regulator valve regulates pressure within the specified range (control characteristics) on the low pressure side.
- So that the A/C compressor is not damaged when refrigerant circuit is empty, the magnetic clutch is switched off and the A/C Compressor Regulator Valve N280 is no longer activated (A/C compressor runs at idle with engine).
A/C Compressor without Magnetic Clutch
A/C compressor is driven by vehicle engine via a ribbed belt.
An overload protection (shear) installed in the A/C compressor ribbed belt pulley releases when the compressor sticks and protects the ribbed belt pulley from being overloaded.
The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and relays it to the condenser.
NOTE:
- The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature.
- The refrigerant for which the A/C compressor is designed is listed on the manufacturers plate. A regulator valve regulates pressure within the specified range (control characteristics) on the low pressure side.
- On this A/C compressor, the control valve is activated from outside.
- The engine should only be started if the refrigerant circuit is completely assembled.
- The A/C compressor is equipped with a protected oil supply, this prevents A/C compressor damage in the event that the system is empty. This means that approximately 40 to 50 cu.cm of refrigerant oil remains in the A/C compressor.
A/C without Magnetic Clutch with Torsion-Elastic Clutch
The A/C compressor is driven directly by the power steering vane pump.
On the A/C compressor driveshaft, there is an overload protection that shears off when the compressor is blocked so that the power steering vane pump remains functional.
The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and relays it to the condenser.
NOTE:
- The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature.
- The refrigerant for which the A/C compressor is designed is listed on the manufacturers plate. A regulator valve regulates pressure within the specified range control characteristics) on the low pressure side.
- On this A/C compressor, the control valve is activated from outside.
- The engine should only be started if the refrigerant circuit is completely assembled.
- The A/C compressor is equipped with a protected oil supply, this prevents A/C compressor damage in the event that the system is empty. This means that approximately 40 to 50 cu.cm of refrigerant oil remains in the A/C compressor.
Condenser
The condenser conducts heat from compressed refrigerant gas to the ambient air.
This condenses the refrigerant gas to fluid.
Evaporator
The fluid refrigerant evaporates in the evaporator pipe coils. The heat required for this extracted from the air flowing on the evaporator ribbing. The air cools off. Refrigerant evaporates and is extracted with the absorbed heat by the A/C compressor.
A defined amount of refrigerant is supplied to the evaporator by a restrictor or expansion valve. In systems with expansion valve, the throughput is regulated so that only gaseous refrigerant escapes the evaporator outlet.
Reservoir
The reservoir collects the vaporized and gaseous mixture coming from the evaporator to ensure the compressor only receives gaseous refrigerant. Gaseous refrigerant is formed from the vapor.
The refrigerant oil flowing in the circuit is not retained in the reservoir as it has an oil drilling.
Moisture which has entered the refrigerant circuit during repairs will be collected by a filter (desiccant bag) in the reservoir.
Gaseous refrigerant is extracted with oil by the A/C compressor.
NOTE:
- Replace the reservoir if refrigerant circuit has been open for a long time (beyond the normal repair time) and moisture has penetrated inside, or if required due to a specific complaint.
- Remove sealing plugs - A - and - B - only immediately prior to installing.
- A desiccant bag in an unsealed reservoir is saturated with moisture after a short period of time and unusable.
- When installing, note arrow for direction of flow if necessary.
Restrictor
The restrictor creates a constriction. This restriction reduces the flow and creates high and low pressure sides in the refrigerant circuit. Before the restrictor the refrigerant which is under a higher pressure is warm. After the restrictor the refrigerant which is under a low pressure is cold. Before the restriction there is a strainer for contaminants and after the restriction there is a strainer, to atomize the refrigerant before it reaches the evaporator.
NOTE:
- Arrow - A - on restrictor points to evaporator.
- Replace after each opening of the circuit.
- Note different versions.
Fluid Reservoir
The receiver collects the fluid drops and then directs them in an uninterrupted stream to the expansion valve. Moisture which has entered the refrigerant circuit during repairs will be collected by the dryer bag in the reservoir.
NOTE:
- Replace the reservoir if refrigerant circuit has been open for a long time (beyond the normal repair time) and moisture has penetrated inside, or if required due to a specific complaint.
- Only remove sealing plugs shortly before installation.
- A dryer bag in an unsealed reservoir is saturated with moisture after a short period of time and unusable.
- When installing, note arrow for direction of flow if necessary.
The new generation of reservoirs are installed directly on the condenser and contain a dryer cartridge.
NOTE:
- Replace the dryer cartridge if refrigerant circuit has been open for a long time (beyond the normal repair time) and moisture has penetrated inside, or if required due to a specific complaint.
- Remove dryer cartridge from packaging shortly before installation.
- The dryer cartridge becomes saturated with moisture and unusable after a short time in an unsealed package.
Expansion Valve
The expansion valve atomizes the streaming refrigerant and controls the flow quantity so that the vapor is gaseous only at the evaporator outlet, depending on the heat transmission.
O-Ring Seals
These rings seal off the connection points between individual components of the refrigerant circuit.
Only O-rings that are resistant to refrigerant R134a and refrigerant oil must be installed. Make sure they are original replacement parts.
O-ring seals:
- Always use only once.
- Make sure diameters - a - and - b - are correct.
- Moisten with refrigerant oil before installing.
NOTE: The color coding of O-rings for the R134a refrigerant circuits has been discontinued. Colored and black O-rings are used.
Refrigerant Circuit Pipes and Hoses
The mixture of refrigerant oil and refrigerant R134a corrodes certain metals (e.g. copper) and alloys and dissolves some hose materials. Therefore use original replacement parts only.
Pipes and hoses are joined together by threaded connections or via special plug connectors.
NOTE: Observe specified torques for threaded connections, use appropriate release tools for plug connectors.
Pressure Relief Valve
The pressure relief valve is installed on the A/C compressor or reservoir.
At a pressure of approximately 38 bar positive pressure, valve opens and closes again once pressure has dissipated (approximately 30 bar).
Refrigerant does not escape completely.
Depending on the version, a transparent plastic disc may be installed which breaks off as soon as the valve is activated.