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Engine Overheating Diagnostics

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When you can't get any heat from your vents.

The most common reason for your vehicle to not have heat is caused by being low on coolant in the radiator, this is assuming the blower motor is blowing air out the dash and that is is just not hot.

Basic Electrical Theory Electrical Components Switches & Relays Wiring Harness Test Equipment Testing with a Multi-meter

There is a chart below to help you understand the Heating System.

Heating System
You may have heard the advice that if you car is overheating, open all the windows and run the heater with the fan going at full blast. This is because the heating system is actually a secondary cooling system that mirrors the main cooling system on your car.

Heater plumbing

The heater core, which is located in the dashboard of your car, is really a small radiator. The heater fan blows air through the heater core and into the passenger compartment of your car.

A heater core looks like a small radiator.

The heater core draws its hot coolant from the cylinder head and returns it to the pump -- so the heater works regardless of whether the thermostat is open or closed.

For more information on car cooling systems and related topics, check out the links on the next page.

1. Introduction to How a Car Cooling System Works 2. The Basics 3. Plumbing 4. Fluid 5. Water Pump 6. Engine 7. Radiator 8. Pressure Cap 9. Thermostat 10. Fan 11. Heating System

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