The typical air conditioning system consists of a condenser, evaporator, accumulator, compressor and high and low pressure lines. They all work in concert with each other to cycle freon, which changes from a gas to a liquid, and then back to gas again. Simplified, the result produces cooled air through the air conditioning vents in the dashboard. Using too much freon or overcharging the air conditioning system produces negative effects that can damage important components, due to excessive pressures.
With air conditioning lines hooked up to a set of gauges for both high and low side connections, too much freon in the system will indicate excess pressure. Normal static pressure on the low and high side with the air conditioning controls off, ranges between 36.3 and 47.6 Kilogram per square inch. Gauge readings more than 25 to 35 PSI on the low side gauge with the air conditioning controls set at maximum, and the engine running between 800 and 1,000 RPMs, will indicate abnormal high pressure. If the high side gauge shows more than 200 to 350 PSI, it indicates excessive high pressure.
Too much freon in the condenser causes the condenser components to work under higher than normal pressure. A rattling or growling noise might manifest itself. Internal damage to the compressor can be very rapid and unexpected. With an overcharge of 10 per cent or more, freon liquid can invade and enter the suction line, damaging the suction valves and crankcase. This noise will be evident as a rattling sound.
Excessive Refrigerant Oil and Heat
Too much freon in the air conditioning systems also means that additional air conditioning lubrication oil has been introduced. Residual oil will collect in the condenser housing and perform like a heat sink by absorbing excess heat. This disallows proper heat transfer and affects the cooling performance.
High Discharge Temperature
Too much freon in the system will backup and flood the inside of the condenser surface area, leading to temperatures typically over 240 degrees. The flooding reduces the condenser capacity, and since the liquid can not be cooled because of the smaller area, the heat and head pressure rises. Too much liquid freon that collects in the bottom of the compressor will also cause high sub-cooling.
An overcharge of freon will cause a reduced mass flow rate through the compressor, restricting its volume output. This will cause extra heat and overload the performance of the evaporator, which would have a difficult time of cooling the incoming warm air. Warm or mildly cool air instead of cold air will discharge through the air conditioning vents.
High Compression Ratios
When the condenser floods as a result of an overcharge, the condensing pressure rises but the volume and flow decreases. This puts undue pressure and stress on the condenser seals and valves, which can fail and lead to a serious freon leak.