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06 - Diagnosis module of air conditioning circuit

Introduction:

Air conditioning is a complex system composed of an air circuit and a closed fluid circuit (cooling loop). The objective of this system is to remove the heat of the air entering the cabin (evaporator). Consequently, this heat is returned to the outside air under the hood (condenser).

To do this, air conditioning do in a closed fluid loop a simple physical principle: The refrigerant absorbs heat in passing from liquid to gaseous state and releases heat in passing from the gaseous to the liquid state.

Circulating within the air conditioning loop, the refrigerant passes successively from the gaseous to the liquid state. These changes allow the fluid state at the circuit of the surrounding air:

- To cool the outside air (or internal recycling if the function is turned on) and send it to the thus cooled inside the passenger compartment.

- Release the heat to the outside.


Good practice

It is important to use air conditioning regularly to avoid the seals drying out, as this can cause leaks in the circuit.

The air conditioning’s functioning and quantity of refrigerant fluid must be checked every year. Over time, the system’s efficiency may deteriorate. A preventive check can reveal a shortage of fluid and any leaks.

Every three years, and whenever the circuit is opened, the drier filter must be replaced. A clogged or damp drier filter does not filter impurities properly and no longer retains the humidity contained in the circuit. This can damage certain components in the air conditioning circuit.


Air conditioning circuit overhaul procedure

A) Not enough fluid

There are two possible cases:


B) Too much fluid

  • Recover the loop’s refrigerant fluid
  • Use the vacuum pump to drain the circuit for 30 minutes
  • Refill the circuit with the manufacturer’s recommended quantity of fluid
  • Add the quantity of oil recovered plus 0.34 fl oz (use the type and viscosity of oil recommended by Valeo)

C) Clogged drier filter

The drier filter must be replaced, as follows:

  • Recover the loop’s refrigerant fluid
  • Check that the drier filter is fitted with its high-pressure connections prior to installation
  • Replace and lubricate the seals before you fit the components
  • Replace the drier filter
  • Use the vacuum pump to drain the circuit for 45 minutes
  • Refill the circuit with the manufacturer’s recommended quantity of fluid

Attention: At the end of this procedure, you will need to add oil to the air conditioning loop (see Procedure for adding oil).


D) Orifice tube and accumulator clogged

Replace the accumulator and orifice tube by doing the following:

  • Recover the loop’s refrigerant fluid
  • Using the appropriate Valeo tool (reference 699930), remove the orifice tube
  • Clean the hose before installing the new orifice tube (fit an orifice tube with the same colour code as the original, choosing the appropriate type for the vehicle’s use)
  • Check that the accumulator is fitted with its high-pressure connectors prior to installation
  • Replace and lubricate the seals before you fit the components
  • Replace the accumulator
  • Use the vacuum pump to drain the circuit for 45 minutes
  • Refill the circuit with the manufacturer’s recommended quantity of fluid
  • Add the quantity of oil recovered plus 0.34 fl oz (use the type and viscosity of oil recommended by Valeo)
  • Refill the circuit with the manufacturer’s recommended quantity of fluid

Attention: At the end of this procedure, you will need to add oil to the air conditioning loop (see Procedure for adding oil).

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