Automotive Heating System Problems

Automotive heating system problems are usually related to the engine cooling system. Hot engine coolant is diverted to the heater core through some type of heater control valve. The core itself fits inside a plastic case and has an inlet hose and an outlet hose.

In most cases both of these hoses are visible from the firewall on the engine compartment side of the vehicle. The inlet hose should be hot when the engine is at full operating temperature. The outlet hose from the heater core should be warm even when the blower motor is on high and the heat mode is selected. When I have a customer complaint about automotive heating system problems like lack of heat in the interior compartment in most cases I find a problem with the cooling system.

Many times I find low coolant due to a system leak. In some cases a stuck open thermostat can also cause this lack of heat condition. When the thermostat is stuck open all of the engine compartment cooling hoses will be cooler than normal.

When there is a problem of insufficient heat it’s a good idea to begin your diagnosis with a visual inspection starting off by checking the coolant level when the vehicle is cold. You have to remember to never remove the radiator cap when the vehicle is hot.

In fact in most cases on modern vehicles there is no reason to remove the radiator cap for just checking the engine coolant level. The only time the radiator cap is removed is when the engine is cold and someone is performing a complete replacement of the engine coolant better known as the drain and fill.

All modern vehicles have a coolant reservoir tank that will have a full mark on it. You can see your owner’s manual for further instructions on where it’s located and how to top it off along with what type of coolant to use. If the fluid is at the correct level you can begin by testing for the proper engine temperature. You start the engine and allow it to warm up to full operating temperature. You select the heat position on your climate control and turn the blower on high.