Is My Car’s Cooling System and HVAC The Same Thing?

Is my car’s cooling system and HVAC system the same thing? I often hear this question because some people use the terms interchangeably. In truth, they are actually different systems that perform different tasks. Think of it this way: the car’s cooling system cools the engine, and the HVAC system cools the driver (and passengers). However, there is a bit of overlap because some of the components work with both systems. Remember, the cooling system relies on coolant in the radiator to cool the engine, while your HVAC uses refrigerant to cool the cabin. Below is more detailed information on both systems.

What Does The Cooling System Do?

Your car’s cooling system works hard to absorb and dissipate the heat created by the combustion engine. It keeps the engine’s temperature operating at acceptable levels so the components providing power are not damaged. The cooling system must operate correctly whenever your vehicle is in use.

Cooling System Components

Your car’s cooling system uses the coolant in the radiator and pumps it through the system in a never-ending cycle to absorb excess heat from the combustion engine. Let’s review the basic cooling system components to see how this process works:

Radiator

The engine radiator includes two parts: the aluminum core, which consists of horizontal or vertical flat tubes and fins that dissipate heat, and the plastic tanks on either end, which allow the coolant to flow in and out of the core.

Radiator Fan

The radiator fan provides a constant flow of air to cool the radiator, even when your car is stationary.

Water Pump

A water pump keeps the coolant moving continuously while the engine is running.

Coolant

The coolant used in modern vehicles is a 50/50 mixture of antifreeze (usually ethylene glycol) and distilled water. Antifreeze also contains chemical additives that inhibit rust and lubricate all the cooling system components.

Seals, Gaskets, Hoses

Several seals, gaskets, and hoses connect all the cooling system components. The main ones are the water pump seal, head gasket, and the upper and lower radiator hoses. 

What Does The HVAC System Do?

Your car’s HVAC system operates the air conditioning, heater, and defroster. This system is the interior climate control. It manages the cabin temperature and moisture levels for driver comfort and to aid vision (foggy or icy windshields). While the HVAC operation depends on a functioning cooling system, it is considered a different part of your vehicle. Let’s take a closer look at the HVAC’s components:

HVAC System Components

The HVAC system has three main components (compressor, condenser, evaporator) and a handful of secondary parts. The system is pretty complex, requiring all the components to work in unison.

AC Compressor

The compressor’s primary function is to keep the refrigerant moving through the HVAC system, like a pump.

AC Condenser

The AC condenser looks and performs much like a smaller version of the radiator in your vehicle. Air flowing across the AC condenser tubes cools the hot refrigerant that has absorbed heat from inside the car. It is usually mounted behind the front grill and near the engine radiator.

AC Evaporator

The AC evaporator works like an ice box, allowing hot air to flow through it. The hot air rapidly cools down and blows into the cabin through the dashboard vents.

AC Cooling Fans & Blower Motor

Cooling fans and blower motor work with the condenser by moving large volumes of air.

HVAC Refrigerant

The refrigerant is a special fluid in the HVAC system that changes back and forth from gas to liquid depending on its temperature. This fluid creates that wonderfully cold air when you turn on the air conditioning.

Cabin Air Filter

The cabin air filter removes air-born pollutants before they reach the interior. It cleans the air in the HVAC system and is often located behind the vehicle’s glove box.

What They Have In Common

This is where things get a bit complicated. The systems have some overlapping, multi-tasking components. The heater and defroster in the HVAC system use some cooling system parts to get the job done.

Heater

Your car’s heater controls are part of the HVAC system. When you turn it on, the water pump directs hot coolant from the engine’s cooling system into the heater core. A blower motor operates the fan that moves the heated air from the heater core into the cabin through the HVAC vents. So, you can see how the heater core works in concert with the engine cooling system.

Windshield Defroster

The HVAC system turns the windshield defroster on and off. The blower motor and fan move large amounts of warmed air from the engine cooling system onto the windshield. This warm air dissipates built-up condensation on the inside of the glass. It also helps melt frost and ice on the outside of the windshield. As the car engine heats up, the air gets warmer due to the coolant (in the cooling system) heating up. That’s why you usually have to ‘warm-up’ your car in the winter for a few minutes before the defroster is effective.

Routine Maintenance & Diagnostic Service

If you need routine maintenance or diagnostic service for your car’s cooling system or HVAC, let Fisher’s Automotive assist you. Our experienced technicians have provided exceptional and reasonably priced auto services to the Kirkland, WA, area since 1979.

Schedule Cooling System | HVAC System Service

Call us at (425)441-3601 or visit our website to schedule your next appointment. We will check your coolant levels, inspect your radiator, and ensure your AC refrigerant is good to go.