Will Heater Work Without AC Compressor in Car

Will Heater Work Without AC Compressor in Car

The heating and air conditioning systems play crucial roles in maintaining a pleasant environment inside the car. However, have you ever wondered about the relationship between these systems? Will heater work without AC compressor in car?

Yes, in most vehicles’ the heater works without an AC compressor. But there are a few factors you need to consider to determine whether the heater will work exactly without an AC compressor or not. 

In this article, we will delve deep into the topic “will heater work without AC compressor in car”. By the end, you can exactly determine whether the heater will work or not without the AC compressor.

How Does the Heater work in a Car?

You know a lot of heat is generated in the internal combustion process of the engine. The car heater works by using that heat. Here is the process:

Engine Heat GenerationHeat is generated during the internal combustion process
ThermostatRegulates engine temperature
Coolant CirculationThe thermostat opens when the engine temperature rises
Water PumpCirculates coolant throughout the engine and radiator
Heater CoreReceives hot coolant from the engine through heater hoses
Blower MotorForces air through the heater core
Heat TransferThe heated air is blown into the car’s interior via vents.

Let’s dive in.

Engine Heat Generation

The engine produced heat when running. The coolant circulates through passages in the engine, absorbing heat to prevent overheating.


Thermostat of a car

The thermostat is for regulating the temperature of the engine, and it is located on top of the engine. It can be identified by following the upper radiator hose, and it maintains the temperature of the engine at around 195 degrees Fahrenheit.

Coolant Circulation

When the engine is going to rise above the ideal temperature, the thermostat opens. Then heated coolant flows out from the engine through the lower radiator hose.

Water Pump

The water pump circulates the coolant throughout the engine and into the radiator. It has to maintain a continuous flow of coolant.

Heater Core

The heater core is located inside the car’s cabin, and it looks like a small radiator. It receives hot coolant from the engine’s cooling system through the heater hoses.

Blower Motor

The blower motor flows air through the heater core, and the speed of the blower motor is adjusted by the controllers on your dashboard.

Heat Transfer

As air passes through the heater core, it absorbs heat from the hot coolant. Then that heat was blown into the car’s interior through the vents.

What Is an AC Compressor?

The air conditioning compressor’s role is an essential component in an air conditioning system. It compresses and circulates refrigerant to absorb heat from the air inside the vehicle.

What Are the Effects of Malfunctioning AC Compressors?

You can experience the following signs if your AC compressor malfunctions.

Decreased Cooling Performance

As I mentioned above, the compressor is responsible for circulating coolant to absorb heat. If it malfunctions, cooling becomes low or even blows warm air from the air vents.

Strange Noises

You can hear unusual noises such as grinding, squealing, or rattling if the compressor is faulty.

Increased Fuel Consumption

If the AC compressor is problematic, it puts a lot of strain on the engine crankshaft. In modern vehicles, it affects the serpentine belt. The serpentine belt rotates the pulleys of most of the components of the vehicle, including the alternator. When strain is put on the engine, you know mileage reduces.

Engine Overheat

When the compressor puts a strain on the engine, heat increases rapidly and can even overheat.

Electrical Issues

A faulty compressor clutch can cause fuses to blow and wires to melt.

Leaking Refrigerant

Leaking refrigerant not only affects cooling performance but can also be harmful to the environment.

So to prevent the above issues, you should repair or replace the AC compressor, or you can bypass it using a serpentine belt.

Will Heater Work Without AC Compressor in Car?

Car heater turned on, indicator light is illuminating

So, will heater work without AC compressor in car? Yes, heater works without the AC compressor in most cars and they work independently.

What about other vehicles? Some vehicles, and on some occasions, it will not. Here are the factors that prevent the heater from working without the AC compressor:

Shared Components

The AC compressor and the heater share certain components within the HVAC system. They are the blower motor, ductwork, controls, and evaporator. If your AC compressor stops working due to a problem with the above components, the heater will also stop working.

Climate Control Integration

The climate control system in modern cars automatically adjusts the temperature inside the car. In such systems, both a heater and an AC compressor are needed for the climate control task. So, one will affect the function of the other.

Cooling System Dependency

In some car models, the heating system relies on the cooling system to regulate the temperature. Therefore, the AC compressors’ presence is necessary for the proper functioning of the heating system in those cars.

Electrical System Problem

The AC compressor and the heating system may share electrical connections and controls. This integration can affect the operation of one system if there are issues with the other.

This video will help you if the heater does not work in your car and show you how to diagnose the problem.


Is it good to use heater in car?

To keep passengers warm and cozy while traveling, a car heater is a necessary component. The majority of car heaters warm the inside of the vehicle with heat from the engine. Other systems employ a heating element powered by electricity to warm the cabin.

Does car heater increase fuel consumption?

Many people are unaware that turning on the heat has no impact on how much gas the car uses. But the heater can drain the car battery.

Does an AC compressor increase fuel consumption?

The added strain on the engine caused by an air conditioning system can result in a 15-20% increase in fuel usage. The actual load is influenced by several factors, including the interior volume of the car, the weather outside, and other elements.

Where is the AC compressor in car?

The AC compressor is located in the engine compartment. You can find it in the front of the engine, towards the middle section. The AC compressor is driven by a belt connected to the crankshaft or pulley of the AC compressor by the serpentine belt.


Will heater work without AC compressor in car? Yes, but it depends. I hope you understand the factors that affect the heater’s ability to work independently. Have a nice day!

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