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What do the various Coolant and Air Conditioning components do?

Radiators - Your car engine generates an enormous amount of heat.  If the engine block gets too hot the pistons will generate excessive friction and run the risk of seizing the engine.  In order to keep the engine temperature to manageable levels, water and anti freeze are passed through the engine absorbing heat and taking it to the car radiator where it is dissipated.

Expansion Tank - The expansion tank is a vital part of your car’s cooling system and acts as an overflow reservoir catching the water/coolant mix that is forced from your radiator as it heats and builds pressure in the system.  As you run your car, the temperature of the coolant circulating through the water jackets naturally increases causing increasing pressure in the cooling system.  Most of the coolant that is forced into the expansion tank returns to the radiator naturally after a few hours or when the engine is cold.

Radiator Cap - The radiator cap is a pressure release valve designed to build cooling system pressure at extreme heat.  Normally designed to hold between 8 and 15 PSI, it’s important that radiator caps have the capacity to maintain sufficient pressure.  An under-pressurised system may result in the car overheating.  So that the system doesn’t become too pressurised, at maximum PSI the radiator cap valve opens and coolant escapes through the overflow tube into the bottom of the overflow tank.

Thermostat - Car thermostats help to keep the engine warm, as well as in regulating the coolant to keep the temperature down.

Thermostat Housing - The thermostat housing is the essential covering designed to protect the thermostat and ensure that your car runs at a proper working temperature.  At one end is the thermostat, which usually sits on the lower intake manifold.  At the other end of the thermostat housing is the radiator top hose.

Cooling Fan - When the temperature of the coolant rises above a set level, perhaps if the car is stationary and there is no cool air moving through the grill to dissipate heat from the radiator, the fan kicks in, blowing cooler air through the radiator to help the cooling process.

Coolant Sensors - The job of the cooling fan sensor to identify the coolant temperature properly and start the cooling fan to protect the engine if the coolant is too hot.  When the coolant is back down to a manageable temperature the sensor stops the fan.

Water Pump – It’s vital that your engine operates at a proper working temperature. Car engines can get extremely hot and quickly suffer serious damage as a consequence.  The job of the water pump is to draw hot water from the engine and circulate it around to the radiator to cool before re-entering the engine.

Coolant Hoses - These hoses are made from rubber and are designed to withstand the high temperatures and extreme pressure to carry coolant around the cooling system.


Compressor - Usually resembling a pump with large rubber and steel hoses It’s your car compressor that supplies the power to a vehcles AC system as well as pressurising and circulating the heated refrigerant vapour

Condensers - The task of the air conditioning condenser is to change the refrigerant from gas to liquid and expel heat from the car.  Normally located in front of the radiator, Condensers take hot air from the compressor and use air flowing through it to removes heat from the refrigerant.  The radiator’s cooling fans move the air through the condenser when the car is stationary.

Evaporators - Like the condenser, the car evaporator is designed to remove heat from your car.  Unlike condensers car evaporatorsare located inside the passenger compartment.  The evaporator receives cool liquid refrigerant which has been cooled by change of state in the condenser, the warm cabin air flows through the evaporator which causes the air to cool and liquid refrigerant to increase in temperature and change to vapour.  The Vaporised cold, low-pressure air absorbs heat from the cabin and swaps it for cool air that is blown in.

Accumulators and receiver driers – Air conditioning accumulators are used in car air conditioning systems that have an orifice tube to meter refrigerants to the evaporator.  An air conditioning accumulatoris your air conditioning system’s main protection against any damage caused by moisture, particularly liquid refrigerant.  Accumulators also remove debris and moisture from air conditioning systems, but their main role is to store excess liquid refrigerant and thereby isolate the compressor from any potentially damaging corrosive acid formed by liquid refrigerant mixing with moisture.

Pollen Filter - A Pollen Filters job is Keeping your car comfortable and ventilated you must make a point of regularly changing your pollen filter.  Heater fans rely on a clean air flow so be aware too that any restriction caused by leaves, bugs and debris blocking or clogging pollen filters can shorten their life-span.