All vehicles use the same parts in the air conditioning system. The vehicles will have a compressor, condenser, evaporator core, high-pressure lines, low-pressure lines, a dryer or accumulator, and an expansion block or an orifice tube.

The dryer and accumulator perform the same function. The name varies depending on where the part is located in the system—before or after the condenser.

The expansion block and orifice tube also perform similar functions. Both are located near the evaporator core.

When working on a car’s air conditioning system, the dryer/accumulator and orifice tube/expansion block must always be replaced. They become contaminated as soon as you open the system to the atmosphere.

Air conditioning problems include:

• The blower motor resistor is blown on one or more circuits.
• The refrigerant is low.
• The system is clogged.
• The system has too much pressure. Many problems could cause this, including dirt in the system or a malfunctioning part.
• The door control system is broken.
• The belt is too worn to turn the air compressor.

Any component could leak refrigerant or have a clog with crud from a worn compressor. The condenser is like a small radiator; it could leak around the tanks or fins. The compressor clutch could be worn, or the veins in the compressor could be collapsed.

The heating system may vary from model to model, but the basic premise is the same. Hot water circulates through heater hoses from the radiator and through the heater core, which is usually located under the dash.

If you have a problem with the heat, it could be:

• The engine is low on antifreeze.
• The water travels too fast through the system and does not have time to heat up to the proper temperature. Generally, the thermostat is the problem here.
• The door control system is broken.
• The control that switches from heat to air conditioning is broken.
• The blower motor resistor is blown on one of the circuits.
• The evaporator core is leaking. If this is the case, the antifreeze will be low, and your vehicle may overheat.
• The water pump is not turning. The vehicle will also overheat.