The aim of this page is to provide some insight into the complexities of automotive a/c units, to help consumers better understand why we can't give a diagnosis over the phone or give a rough idea of cost sight unseen.
The Evaporator:
a plastic box containing fine metal fins like your radiator, located behind your dashboard, removes heat from the cabin or exterior, as heat is attracted across the fins into the cold liquid refrigerant inside.
This heat movement adds energy to the refrigerant, rapidly raising the temperature its temperature until it changes into a gas (like water accepts heat until it comes to the boil then converts to steam). The air with heat removed is then pumped into the vehicle via the vents.
The Compressor:
a mechanical pump pressurises and drives the refrigerant around the system. The compressor pumps the gas, formed by the evaporator to the condensor.
The Condenser:
another heat exchanger, located in front of your vehicle's radiator. Heat is released across these fins from the hot, pressurised refrigerant gas to the colder outside environment. Heat transfer is assisted by a cooling fan. As the refrigerant passes through the coils of the condenser, losing energy, it condenses into a hot liquid.
The liquid passes through the receiver-drier which absorbs any harmful moisture and acid.
The dried, high pressure liquid is then forced through the expansion valve. The valve regulates the delivery of the high pressure liquid as a spray into the relatively low pressure environement of the evaporator.
This dramatic loss of pressure causes the liquid to lose a lot of heat allowing it to received new heat across the fins of the vehicle's evaporator - starting the whole process again.
All of these components are interconnected by flexible hoses.
If any one of these components fails, it causes changes in the critical temperature/pressure relationship required to make heat transfer, and hence air-conditioning work.
The Controller Panels:
mechanical or electronic controls on your dashboard let you regulate your system's performance to meet your comfort needs. Electrical circuits, sensors and protections devices may shut the system down if it's not operating correctly.
Pollen Filters:
Trapping dust, pollen and some odours, pollen filters get blocked up over time reducing air flow and cooling at which stage they need replacement (annually or approximately every 20,000 km).
