Climate Units - Design and Function (Convertible): Specifications Volvo C70 I

Checking the capacity and function of the air conditioning system

Compressor

In principle there are three reasons for a compressor not starting

1. a fault in the magnetic clutch.
2. incorrect pressure in the system (too low or too high).
3. fault in the wiring or the compressor control system.

Performance test

The performance test provides an indication of the air conditioning system capacity. During the test the temperature of the air flowing out of the center dashboard vents is measured under predetermined conditions (engine speed (RPM), fan speed, control settings etc).

If the capacity is too low this may be due to a number of "external" reasons, for example

1. slipping compressor drive belt.
2. insufficient air flow to the condenser (blocked by insects/dirt, foreign objects).
3. poor engine cooling fan (FC) function.
4. insufficient air flow to the climate control system (duct blocked by leaves etc).
5. poor blower fan function.
6. incorrectly adjusted control/damper/water valve for airflow - recirculation - temperature.

Too low capacity can also be caused by "inner" causes (faults in the system).

Initially this is checked by

1. visual check (damage, leakage. In the event of leakage there is often excess oil = greasy surface).
2. listening (there is always a little noise in the system when the refrigerant changes between gas and water form at different pressures).
3. feeling the components (if there is cold/warm air, how cold/hot they are).
4. measuring the pressure in the system (if possible measurements should be taken on both the low and high pressure sides).

Scheme 380

Remedy immediately!

Any leakage must be remedied immediately in order to prevent moisture, air or foreign particles entering the system. In addition it is vital that working conditions are kept clean and dry.

If dirt has entered any component it must be cleaned or replaced.

In the event of collision damage, all components that may have been damaged must be checked thoroughly. Soldered joints must be checked extra carefully.

Note. Damaged hoses/pipes must be replaced. They must not be repaired.

Use plugs!

Protective plugs must be used as soon as a connection is separated. The plugs must be removed as late as possible (directly prior to connection).

This is especially important for the receiver drier and evaporator.

A plug kit is available as a replacement part.

The oil is hygroscopic (= moisture absorbent) and must therefore be stored in a seal container. This is especially important for PAG oil.

O-rings, threads

If a connection is taken apart the O-ring(s) must be replaced.

Note. Different O-rings depending on the type of refrigerant.

O-rings and threads must be lubricated with the correct type of oil prior to installation.

Replacing the receiver drier

If the system is opened the receiver drier must be replaced

1. if air has entered the system for longer than 10 minutes.
2. if it is suspected that there is moisture in the system.
3. if the receiver drier is more than 1 year old.

The receiver drier should usually be replaced on most of the occasions that the system is opened.

This is because the drying agent is not reversible. It is not possible to extract water from the drying agent by vacuum pumping the system.

Topping up oil

Too much oil reduces cooling capacity.

Too little oil will damage the compressor.

The oil must be topped up when repairing a leak or when replacing a component.

The amount of oil required depends on the extent of the leak, whether it was large or small and on which components are replaced.

There are different oils depending on the type of refrigerant and compressor.

Some of the effects of too much water in the system

Internal corrosion ("rust")

Corrosive damage, applies in particular to systems with R12.

At high temperatures water functions as a catalyst for the break down of R12. Chlorine in R12 then compounds with the water and forms hydrochloric acid (=corrosive damage).

Poor power, interrupted operation (the compressor is disengaged for long periods).

The water freezes to ice at low temperatures and blocks the system, for example in the expansion pipe. As a result the pressure in the high pressure section increases and the safety switch disengages the compressor. It is then disengaged until the ice melts and the pressure has dropped.

Damage to the compressor (breakdown, reduced service life).

Liquids cannot be compressed so drops of water increase the load on the compressor.

Difficulties extracting the water from the system when vacuum pumping.

When the pressure sinks the water evaporates. Because pipes and hoses are poor conductors of heat, the heat (energy) required for evaporation is obtained from the water. As a result the water is over cooled and freezes to ice, blocking the system.

Scheme 381

Use overalls, goggles and rubber gloves

The refrigerant used has a low toxicity. The main risk is from frostbite caused by coming into contact with refrigerant. Protect your eyes and skin!

In the event of refrigerant coming into contact with eyes

1. Rinse immediately with clean water for at least 10 minutes.
2. Contact a doctor in the event of problems with vision or other difficulties.

In the event of refrigerant coming into contact with skin

1. Rinse with warm water.
2. Contact a doctor in the event of problems with vision or other difficulties.

Avoid high temperatures and mixing with air

Ensure that refrigerant does not come into contact with naked flames, welding, electrical discharges or hot metal surfaces etc.

Do not smoke when working with refrigerants.