Home Central Air Conditioner

Refrigerant

There are 2 different types of air conditioning refrigerant currently used in residential cooling systems. R-22, commonly referred to a Freon and R410A, a blend considered to be more environmentally friendly, sometimes called Puron.

R-22

R-22 also known as Freon has been used for decades as the refrigerant in central air conditioning systems. However it has been linked to Ozone depletion and has therefore been banned from being manufactured after the year 2010.

R410A

Refrigerant of 4xx series, e.g. R-404a are non azeotrope type refrigerants, EXCEPT for R-410.

R-410 is a near azeotrope mixture. Azeotrope refrigerants consist of more than one blend of refrigerants, but it acts like a single refrigerant. Non azeotrope refrigerants on the other hand, DO NOT act like a single refrigerant.

You cannot add a charge to a non-azeotrope refrigerant system. If low, the remaining refrigerant needs to be completely evacuated and the system has to be charged again from zero. This is because of the physical properties of the different chemicals being lost from the system at different rates. The blends will be lost from the system at different proportions due to different boiling temperatures, whenever there is a leakage in the non azeotrope refrigerant.

Azeotrope, or near azeotrope blends will act as a single refrigerant, and therefore, may be topped up in case of refrigerant leakage. R-410A, just like R-22 can be topped up.

Pump Down Procedure

You will need a set of refrigeration gauges and a means of closing whatever types of service valves are on your unit. You will also need to know what order in which to close those valves and what the readings on the gauges are telling you. The pump down procedure only takes a couple of minutes.

There are two valves at the condenser, one valve for the suction line and one valve for the liquid line. Close the liquid line valve and turn the air conditioning on. The compressor pumps all the refrigerant into the condenser coils. Watch the gauges carefully and when the pressure gets to zero on the gauges quickly close the suction line valve to trap the refrigerant in the condenser. Now quickly turn the compressor off. This saves using refrigerant unnecessarily because the same refrigerant in the system can be reused for the new evaporator coil or air handler.

After the new evaporator coil or air handler is installed you need to evacuate the new part of the system. When evacuation is completed open the valves to allow the refrigerant into the new part of the system. To make sure the charge is correct use the gauges and the superheat method or subcooling to ensure the proper amount of refrigerant is in the system.

Troubleshooting

Blowing Warm Air & A-Coil Not Frozen

Low on coolant. Refrigerant doesn't require periodical charging. It is not a consumable item within an air conditioning unit, unless, there is a leak within the system. Given that it worked previously, and now it is not working, it is likely there is a leak in the system.

Blowing Warm Air & A-Coil Iced Over

The A-Coil can freeze up, building up ice and lowering efficiency. When completely frozen over it will not function. One cause if this happening is lack of circulation, due to the fan malfunctioning or insignificant fan speed, or and undersized blower. Increasing air circulation though the system can prevent the A-Coil from freezing over.

If the air conditioner is not properly charged, such as too much or little coolant (pressure) then the system may operate in an inefficient way and also cause the A-Coil to freeze up.

Turn off the unit and allow the A-Coil to thaw completely. Make sure the tray below the A-Coil is not pooling with water. It should be able to drain out a hose.

Refrigerant Leak Detection

A leak in the air conditioner tubes will pose the threat of refrigerant loss and finally, no cooling.

There are three common leak detection methods at end user level.

• Soap test
• Electronic leak detector
• UV light test

Electronic leak detector is the most widely used method nowadays, with lightweight construction, and accurate pin-pointing of the leak position on the tube, or other air conditioner parts.

Treatment for leaks is either part replacement, or repair by tube soldering, or welding.