History

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If you are lucky enough, you’ll have a system in your car that lets us enjoy the same level of comfort that we enjoy at home and at work. It is Air Conditioning.

Some of the benefits are:

  1. Cooling on a hot day
  2. Demisting your windows on a damp day
  3. Filtration of airborne particles, e.g. pollen and dust
  4. The occupants of the vehicle are less stressed and arrive at journeys fresh and relaxed.

In the modern world we live in, our customers are often worried about using extra fuel using the A/C system. Modern vehicles A/C systems are highly designed for efficiency, however, a routinely serviced A/C system will add very little to the fuel consumption.

Consider however, that just opening the windows will drastically affect the vehicle’s aerodynamics which in turn will use lots more fuel, opening the windows also creates noise pollution within the vehicle, and there is a benefit in today’s society to the added security of having the windows wound up.

At the flick of a switch or the push of a button, we go from unbearable heat to comfortably cool air. This ‘Comfort Zone’ within the vehicle is normally between 18 Degrees C, and 21 Degrees C.

The system achieves this by cooling the ambient air, and de-humidifying the passenger compartment. We don’t even think about it too much unless something goes wrong. We at ‘Bee Cool’ think that everyone should be cool in their car!!

The History Timeline

Air conditioning in cars first arrived over seventy years ago in 1939. The first refrigerated Air Conditioning system was fitted to the 1939 Packard.

The Packard advertising slogan was ‘Forget the heat this summer with the world’s only air conditioned car’.

Cadillac was the next manufacturer to follow in 1941 and during this year 400 Cadillac’s were sold with air conditioning as a very expensive option. In order to turn off the air conditioning, you had to open the bonnet and remove a drive belt!!

The air conditioning systems in use then were crude by today’s standards, but did supply some measure of relief from the heat.

In the years that followed there were some improvements, such as computerized automatic temperature control (ATC), otherwise known as Climate Control, that allow you to set the desired temperature and have the system adjust automatically and improvements to overall durability.

This has also added to the complexity of the air conditioning system as well. In 2010, industry statistics say that 80% of vehicle’s coming off the production line have Air Conditioning fitted as standard fitment.

In addition to the complexity of the new air conditioning systems, there are tighter environmental regulations that govern even the simple process of adding refrigerant to a system.

Scientific studies have established the fact that R-12, a CFC, does damage the ozone layer and the United Kingdom and many other countries have banned its use and manufacture.

These countries have joined together to sign the Montreal Protocol, a landmark agreement that was introduced in the 1980′s to limit the production and use of chemicals known to deplete the ozone layer, and more recently the Kyoto Agreement, which came into effect in February 2005.

This has led to most cars produced today using a more environmentally friendly refrigerant R134a, a HFC, and less damaging to the environment. From 2011 vehicle manufacturers will have to adopt a new refrigerant, HFO-1234yf, which again is safer for the environment.

Should you have a vehicle produced before 1994, or an import, you will have an R-12 air conditioning system, and you may have heard of new words and terms like “retrofit” and “alternative refrigerant”.

You may be given an option of “retrofitting” as opposed to merely replacing the entire system to use R-134a.

In 1992, a new type of refrigerant for automotive air conditioning systems began to appear in new vehicles.

R-134a was introduced to replace R-12 because R-12 contains ozone-damaging chlorofluorocarbons (CFCs). R-134a is ozone-friendly because it contains no CFCs. It is also non-toxic and non-flammable, and meets all of the Environmental Protection Agency’s criteria for alternative refrigerants.

By 1995, all new vehicles were factory-fitted with R-134a air conditioning systems after the production of R-12 was phased out, and today this refrigerant is illegal in the UK.

Retrofitting involves making any necessary changes to your system, which will allow it to use the new industry accepted, “environmentally friendly” refrigerant, RS24.

This new refrigerant which was developed by DuPont primarily for Rolls-Royce, has a higher operating pressure, therefore, your system, dependant on age, may require larger or more robust parts to counter its inherent high pressure characteristics.

If not performed properly, may reduce cooling efficiency that equates to higher operating costs and reduced comfort.

It is important to note that you CANNOT use R134a in a R12 system for several reasons.

The molecular size of the refrigerant is not compatible, meaning that R134a will leak from a system that is designed for R12, in the same way that water pours through a sieve. The component used as a desiccant in the Filter-Drier will not be compatible with another type of refrigerant.

The lubrication oil contained in the systems are different, R12 systems use a mineral oil, and R134a needs a Pag oil. You cannot mix these two, as a reaction will take place within the system, and the oil will emulsify, and fill the system with something which looks rather like cottage cheese!!

Beyond these reasons, the operating pressures of the refrigerants are completely different, and the compressors is designed to work at a specific pressure, as well as all of the systems barrier hosing etc.

If you have a R12 system, do not despair, we at Bee Cool are familiar with these systems, and are fully trained to service your system using RS24 and mineral oil. We will soon have your system performing just like it did when it was new.

The reason vehicle manufacturers choose R-134a to replace R-12 is because R134a comes closer to the cooling properties of R-12 than any other alternate refrigerant. Even R-134a is so close to R-12; it is not a direct replacement.

They are chemically different and incompatible because each requires a different type of compressor oil and desiccant. Since they are different the current law prohibits mixing the two to prevent cross contamination.

It is also a legal requirement that air conditioning technicians are required to recover and recycle R-12 whenever they perform any repairs to an R-12 system. Even though they are different, R-134a can be used in an R-12 system provided the system is converted or “retrofitted” to the new refrigerant.

The way this is done will vary from one vehicle to another, but in most cases it will require factory R-134a systems that are generally equipped with barrier style hoses to reduce seepage that can lead to refrigerant loss over time.

It may not be necessary to replace the hoses when converting an R-12 system with non-barrier hoses to R-134a as long as the hoses are in good condition.

This is because the hoses have absorbed oil that forms a barrier of its own. But if the old hoses are leaking, they should be replaced with new barrier style hoses. Factory R-12 systems generally use mineral oil while R-134a systems use various types of PAG (poly-alkaline glycol) oil, because mineral oil does not mix with R-134a and PAG oil does not mix with R-12.

Some conversions also require replacing the high-pressure cut-off switch and/or orifice tube or expansion valve with ones calibrated for R-134a.

The EU banned the use of refrigerants with a Global Warming Potential (GWP) greater than 150 in all new vehicle platforms from 2011. R134a refrigerant has a GWP of 1300. For 5 years the automotive industry had been developing CO2 systems, which have a GWP of 1, but the cost, reliability, and safety, did not meet industry needs.

There is also an issue regarding credits towards the ‘Corporate Average Fuel Economy’, (CAFE), regulations requiring a minimum MPG of 34.1 for all vehicle’s by 2016.

Some OEMS will require these credits to off-set fines incurred from a non-compliant fleet. HFO-1234yf has a GWP of 4.

It has been co-developed by DuPont and Honeywell, and will replace R134a for vehicles in the next generation. There are however, some service differences, these being that all service equipment must meet J2843, J2851 VDA Requirements.

This will mean new recovery, recharge, refrigerant identifiers, and leak detection equipment. HFO-1234yf system components cannot be replaced with any other ones using a different refrigerant, or from salvaged vehicles.

Any replacement evaporator will have to meet the new standard for the proposed ISO 13043 and/or SAEJ2842. Most importantly, HFO-1234yf is mildly flammable, and all precautions used with other flammable substances will be applicable.

THE HFO/1234YF DILEMMA

On November 23rd 2012 the European commission ruled that after 1st January 2013 R134A which has been in use since 2004 as the main refrigerant for automotive a/c systems will not have type approval for manufacturing. The new gas that has been jointly developed by Honeywell and DuPont is called HFO 1234YF and must be fully adopted by manufacturers as standard refrigerant by 2017.

By the end of 2012, Daimler/Mercedes had released press statements regarding the potential flammability risks of HFO, putting the manufacturing industry into turmoil. Essentially all the time and money spent in research and development on this product will be wasted.

By February 2013 Daimler/Mercedes Benz, Audi, & BMW officially leave the HFO development program stating the concerns over vehicle safety.

Daimler/Mercedes Benz recalled the SL class (R231) built with HFO platforms with the intention of rebuilding the sold vehicles to R134A.

By June 2013 the European commission granted the manufacturers an extension for the type approval and for further safety testing of the HFO product.

In August 2013 the German safety authority (KBA) supported Mercedes Benz in their decision not to adopt HFO and this was supported by the French government’s decision to block registration of new vehicles containing HFO.

As of January 21st 2014 the European commission is preparing proceedings against any manufacturers using 134A in their vehicles.

There are then three documented proposed alternatives currently being considered:

System 1

TIFFE – (Thermal Systems Integration for Fuel Economy)

This is a joint collaboration between Fiat, Ford Germany & Denso the system offers both engine cooling and air conditioning, combining both current systems and utilising a heat exchanger. There are both positives and negatives to this system.

The positives are that a heat exchanger does not have to be mounted at the front of the vehicle for maximum airflow, but can be mounted under the vehicle allowing for more aerodynamic design concepts. The system does not require engine power. And therefore is suited for Hybrid technology vehicles it also has an academic fuel consumption of approximately 28% due to homogenous consumption.

There are also some negatives firstly the system takes three pumps to run as opposed to the current single compressor, this means that there could be future warranty and servicing implications due to this added component. There are potential problems with long term reliability due to additives that are required to be added to the system. Finally there would need to be new refrigerants potentially required to ensure system efficiency.

System 2

R744 (CO2)

CO2 systems are currently widely used in large scale industrial applications. The system is efficient from an academic viewpoint and is known to be reliable. However there are major problems in producing a CO2 system small enough to fit into an automobile. Also CO2 is highly toxic to humans and the potential for leaks and seepage into the cabin of an automobile inevitable illness and even death may occur. This will take a lot of convincing to the current vehicle safety authorities worldwide and manufacturers to adopt.

System 3

R445A (AC6)

This product is manufactured by Mexicem in Mexico it is designed to be a safer, less flammable alternative to HFO-1234YF. The product is still mildly flammable and although better than HFO due to current perception of HFO it would be hard to change the viewpoint of both manufacturing industry and the worldwide vehicle safety authorities. There would potentially be further safety issues further down the line with this product in regard to aftermarket servicing procedures.

Whereas R134A has a boiling point of -26c, R445A has a boiling point of -48c and so carries increased risks of cold burns to servicing personnel in the aftermarket and would be very hard to comply with health and safety legislation in the workplace.

SUMMARY

In summary the three current proposed alternatives to HFO each have significant downsides and there is no easy short term answer. In an ideal world it would be for someone to spend a lot of money on research and development to find a brand new product.

Anyone who was able to develop this ideal product would potentially have not only worldwide sales of that product when fitted to automobiles but also increased brand credibility, revenue form refrigerant and consumables sales both in manufacturing and aftermarket servicing.

The answer does however need to be found quickly and in any event before 2017 to comply with the legislation’s currently in place.

I know that as of today, (1/2/14), currently major motor manufacturers are struggling to find solutions to this problem, and a lot of work is currently being done in R&D, but no solution has yet been found, and I will update this page with further information as I have it.

Recovery of old refrigerant require the handler to have a relevant Hazardous Waste Handling Licence, and to keep full records and dispose of any old refrigerant in line with the rules set out and monitored by the Environment Agency.

A record of a ‘Waste Transfer Note’ must be completed. Any transportation of refrigerant must comply with the Carriage of Dangerous Substances by Road legislation.

All refrigerants carried must have Safety Data Sheets (MSDS) available in case of accident or collision. Environmental Protection Act (1990). Otherwise known as the EPA, under this act it is illegal to deliberately release (or vent) any refrigerant into the atmosphere.

There is an unlimited fine for wilful release into the atmosphere of refrigerant.

COSHH

The Control of Substances Hazardous to Health regulations came into force in 1989.

It is necessary under this act to take essential measures to identify, and control the use of any substance used or present in their place of business which may prove hazardous to health. EC Regulation 2037/200.

This came into force on 1st October 2000, and bans the use of any CFC refrigerant for the maintenance of any existing equipment. Consequently, any vehicle containing R12 which is damaged cannot be re-filled with R12.

A procedure known as ‘retrofitting’ will allow the Air Conditioning system to be converted. F-Gas Regulation.

From 4th July 2008, there is a minimum mandatory qualification for all refrigerant handlers. Legislation introduced on 15/02/08, states that anyone coming into contact or using refrigerant’s will need to have passed a F-Gas and DEFRA approved assessment and training course. Penalties for non-compliance are severe.

The business involved can have equipment confiscated, their business shut down, and or a prosecution with an unlimited fine.

It is important to note that all Vehicle Manufacturer’s state that your Air Conditioning system must be serviced by ‘QUALIFIED PERSONNEL ONLY‘, and is the only part of your vehicle to which this applies.

Do not attempt, under any circumstances to service or maintain your own Air Conditioning system, as it is a high pressure system, and severe injuries can be caused by any attempt to do so.

We at Bee Cool have a company policy to comply with all current legislation and recommended guidelines.You can be assured of the highest standard of competence with Bee Cool, both now and in the future. We are also members of ACRIB (Air Conditioning and Refrigeration Industry Board), and IOR (The Institute of Refrigeration).

Air Conditioning System Design

There are three basic types of air conditioning systems. And as each type is different, the operating principles and designs are similar.

The components that each system has are: the compressor, condenser, evaporator, orifice tube, thermal expansion valve, receiver-drier, and accumulator. We will look at these parts in detail.

  • Compressor

    The compressor is the heart of the air conditioning system. The compressor is a belt driven pump that is fastened to the engine.

    At the front of the compressor is a magnetic clutch which when given power engages the compressor. It is responsible for compressing and transferring refrigerant gas.

    As the compressor is the heart of the air conditioning system, it pumps refrigerant in a closed loop through the system. The moving refrigerant moves heat from inside the vehicle to outside the vehicle.

    The air conditioning system is split into two sides, a high-pressure side and a low-pressure side; defined as discharge and suction.

    The compressor takes in low-pressure vapour coming from the evaporator or in some cases the accumulator and compresses it into a high-pressure liquid and sends it to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.

    The compressor discharges this high-pressure refrigerant through its discharge port to the discharge hose. There are four main types of Compressor; Fixed Displacement, Variable Displacement, Vane, and Rotary (also known as ‘Scroll’).

    All of these types are driven by the engine using a belt.

    There also is a new type of compressor, usually fitted into electric cars, known as a High Voltage Compressor, which is driven by an A/C Inverter instead of the engine. This also uses different lubrication oil, ND11, as it has to contain a high level of electrical insulation.

  • Condenser

    This is the area in which heat dissipation occurs.

    The condenser is usually in front of the radiator and will have much the same appearance as the radiator. The air flowing through the condenser removes heat from the refrigerant that is flowing through it.

    The condenser takes in hot high-pressure refrigerant and cools it. The refrigerant goes in at the top as a ‘Super-Heated Vapour’ and changes to a ‘Sub Cooled Liquid’ as it cools.

    As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high-pressure liquid.

    In a rear wheel drive vehicle the engines cooling fan supplies the airflow required to draw heat from the condenser. In some cases there will be an auxiliary, electric, cooling fan to provide additional airflow.

    On front wheel drive cars there will be one possibly two electric cooling fans to provide additional airflow through the radiator and condenser. There are three main types of Condenser; Fin and Tube, Serpentine, and Parallel Flow.

  • Evaporator

    The evaporator is very similar in function to the heater core, except for the fact that it absorbs heat from the passenger compartment instead of supply heat.

    It is usually mounted under the passenger Side dash and mounted to the inside bulkhead. The low-pressure liquid refrigerant enters the bottom of the evaporator, or a high-pressure liquid that is sprayed into the evaporator by the expansion valve, goes through a rapid evaporation and changes state into a vapour.

    Its primary duty is to remove heat from the inside of your vehicle but the secondary benefit is remove humidity.

    Just as water condenses on an ice filled glass, water condenses on the evaporator. Airborne contaminants entering the system stick to the wet evaporator and are drained to the outside.

    Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same, keeping pressure in the evaporator low and to keep the evaporator from freezing.

  • Pressure Regulating Devices

    The evaporator temperature can be controlled by regulating the refrigerant pressure and flow into the evaporator. There are several ways to do this and the most common are:

    Orifice Tube

    The most commonly used pressure-regulating device is the orifice tube. It is installed either in the inlet tube of the evaporator or in the liquid line between the condenser and evaporator.

    The down side of the orifice tube is that it can become clogged with debris and can be costly to replace.

    Expansion Valve

    Another pressure-regulating device is the expansion valve. The expansion valve can sense the pressure and temperature of the refrigerant, which makes it very efficient in controlling refrigerant to the evaporator.

    There are several different varieties of expansion valves.

    The down side is that, like the orifice tube, it can become clogged with debris and because they contain moving parts can stick or fail over time.

    An important thing to note is that by design the compressors can way out pump the flow of refrigerant through the expansion valve. This is why there is low-pressure from the expansion valve back to the compressor.

    The expansion valve has a capillary tube with a thermal bulb that controls how far open or closed it is. The thermal bulb and the internal pressure of the refrigerant balance to control just the exact amount of refrigerant needed.

    The thermal bulb is clamped to the output of the evaporator. If not enough refrigerant is flowing to cool the evaporator this bulb will sense it and open more or vice versa.

    The Receiver/Filter/Drier

    The receiver-drier is placed on the high side of expansion valve systems. Since this type of valve needs liquid refrigerant to function a receiver is used to ensure that the valve gets the liquid it needs.

    This item provides three functions:

    1. It is a tank that holds excess refrigerant and the refrigerant that leaves it usually goes up a pickup tube and past a sight glass. Under normal operating conditions, vapour bubbles should not be visible in the sight glass, if fitted.
    2. It has a filter in it to remove small amounts of debris from the system.
    3. It has a chemical in it that treats the refrigerant by removing moisture and acid.

    There are different types of receiver-driers and different desiccant materials used in them. Some of these desiccants are not compatible with R-134a and receiver-driers will be marked for use with either R-12 or R-134a.

    Newer type receiver-driers use a special desiccant that is compatible with both refrigerants. R-134a requires a different desiccant (XH7) in the accumulator or receiver/drier because the molecules are smaller than R-12 and quickly fill up the “holes” that absorb moisture in XH5 desiccant.

    This can lead to acid formation and sludging (shows as a milky substance), as well as desiccant breakdown in some applications. It is a good idea to replace the receiver-drier each time the system is opened for repair or anytime moisture and/or debris is of concern.

    Most manufacturers recommend changing this component at least every three years.

    Accumulator

    Orifice type systems use an accumulator that is connected directly to the evaporator outlet and stores excess liquid refrigerant.

    Since liquid refrigerant going into a compressor can do serious damage to the compressor, the main purpose of the accumulator is to isolate the compressor from any damaging liquid refrigerant.

    Accumulators, like receiver-driers, also remove debris and moisture from a system. It is also a good idea to replace the accumulator each time the system is opened for repair or anytime moisture and/or debris is of concern.

© Bee Cool ACS Ltd