A/C condenser
Definition
The condenser is the thin aluminium heat exchanger in front of the engine radiator that receives hot high-pressure refrigerant gas from the compressor and cools it with ambient air into a liquid, giving up the heat absorbed in the cabin; many modern ones integrate the receiver drier cartridge in a side tank. Because it sits at the very front it suffers stone damage, corrosion from road salt that eats the fins and tubes, and blockage by insects, leaves and dirt; internal blockage from compressor debris is also common. A leaking condenser is the single most common refrigerant leak on cars over five years old, often visible as an oily, dirty patch on the fins or found with UV dye or an electronic leak detector; a blocked or dirty condenser causes high high-side pressure, poor cooling at idle or in traffic that improves at speed, and the compressor cutting out on the high-pressure switch. Check that the condenser fan runs when A/C is requested and that the fins are clean and straight; a temperature drop across the condenser of 15-30 °C indicates normal heat rejection. Replace the drier or cartridge with the condenser, use new O-rings with the correct oil and vacuum the system before charging. Codes: P0530-P0534 (pressure sensor, as a result of high or low pressure), P0480-P0483 (cooling fan circuit), B1xxx HVAC codes for high-side pressure out of range; leaks themselves set no codes.