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Charging in the Winter

Using your air conditioning charging station in the winter months can present it's own problems. The refrigeration gas (R134a) does not flow too well if the external temperature drops in the workshop. Some machines have their own on-board heaters but others rely on recovering some refrigerant from the vehicle or from a supply cylinder. One of the benefits of recovering and recycling refrigerant is the heat generated through the compressor. The charging station works exactly the same way as a vehicle; if you draw gas from a low pressure area and compress it, the low pressure side gets cold and the high pressure side gets hot. This hot high pressure liquid that comes from the recovery side gives us a benefit when charging into the car as the liquid races into the system quicker.

One of the drawbacks with charging liquid refrigerant into an evacuated system is as soon as the liquid is released it wants to expand into a gas and equalise the pressure between the car and the charging station. If this takes place before the full charge has been delivered then the station effectively undercharges the car and the charge is not complete. A simple trick to rectify this is to close the red HP valve on the station or the HP coupler and start the car. The compressor on the vehicle will then pull the rest of the refrigerant into the vehicle and finish the charge. The gas charge is usually weighed in from a scale platform on a modern machine and the scale doesn't care how the refrigerant is decanted.

Inside Out

If you find that there is a regular problem with charging then it might be an idea to check that the vacuum pump is in good condition. The oil level and oil condition is critical. The vacuum pump oil lubricates the pump and provides the seal for the pump blades. If the oil level is too low the seal breaks down and the high vacuum required cannot be reached. The quality of the oil is also important.

A poor vacuum can cause many problems because it does not dehydrate the system properly. Any moisture in the cars system can be devastating as the combination of R134a and moisture creates hydrochloric acid. This quickly saturates the filter dryer making it useless and then starts to destroy the whole system from the inside out.

With the Winter months being cold and damp, moisture is very difficult to keep out of an open system, especially if the vehicle has been damaged and stored in compound for a while. Because the system is effectively charged with refrigerant (R134a) as soon as it escapes and evaporates it leaves the inside of the system very dry. Moisture is automatically attracted to the dry areas and considerable amounts of water can form inside the pipes and condenser. This is unavoidable and only an extensive evacuation can rectify it. In this case a new filter dryer must be fitted and the system evacuated immediately. If we break into the system and have to leave it for any length of time then taping the open hose ends up with tape can be a great help. This obviously stops moisture and dust from entering the system and causing unnecessary contamination.

A very cold car can be difficult to recover the gas from. This can be due to the pressure being very low in the system and warming the car up is a great help. Also, if the recovery cylinder has picked up air the pressure increases and the compressor will struggle. As a tip, it is always worth keeping the new supply cylinder near the station so that they are at the same temperature.

For more information or assistance with any refrigerant reclaiming enquiry contact JAVAC.