Modern car air conditioning systems are fairly robust, and with the exception of cabin air filters, the various components that make up air condition systems are generally not considered to be service items that have to be replaced at fixed intervals.
However, while air conditioning systems generally fall into the “If it’s not broken, don’t fix it” category, no system is perfect and parts failures do occur, some of which may cause the system to stop working altogether. Below are some common failures that require repair between services.
Some pressure switches perform two functions; one is to monitor system pressures while the system is in operation, and the other is to function as safety cutout switches. Thus, if one or more pressure switches report abnormally low system pressures, the compressor clutch will be deactivated to prevent damage to the compressor.
Although most refrigerant leaks occur at pipe/hose joints or connections, refrigerant can also escape (albeit very slowly) through degraded flexible hoses. Prolonged exposure to heat, fuel and oil vapours, and vibration attack, and eventually degrade the materials flexible high-pressure hoses are made from. If a flexible hose is degraded enough, refrigerant can escape though minute leak paths in the hose material itself, or through the points where steel fittings are crimped onto the hose, or sometimes, both.
The actual failure involves either disintegration of the bag that contains a desiccant, or saturation of the desiccant that prevents the absorption of moisture and other impurities in the refrigerant. Note though that the replacement of accumulators or receivers/dryersrequires that the system be recharged.
Although compressor failures are relatively rare, improper or incorrect recharging practices can allow moisture to enter the system, which if it happens, will always damage the compressor through the formation of corrosion of internal components.