How to Get the Air Hotter in My Car

by TJ Hinton
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Diminished heat from your car's heater may be caused by several things. When troubleshooting, allow your engine to cool completely before you open the cooling system at any point. Always use the manufacturer's recommended coolant, and never mix coolant types or colors. Many coolants are environmentally friendly, but many are not, so check your coolant type and dispose of it according to your local laws and ordinances.

Circulation Problems

Poor coolant circulation caused by air in the system will prevent the heater from putting out sufficient heat, because the heater core is usually the highest point in the system, so this is where air might collect. This is the first thing to check if you recently drained or flushed the cooling system. Check the coolant level, top it off, and bleed the air out of the system as necessary.

Heater Core Problems

Corrosion and sedimentation can clog up the heater core and reduce the efficiency of the heat exchange rate, causing a loss of output. Compare the temperatures of the heater core input and output hoses. If they are not close, then you probably have a clogged or corroded heater core. Back-flush the core to improve coolant flow. If the aluminum elements within the heater core are corroded or it leaks, you must replace it.

Air Handler Problems

Warm air from the heater core is forced through the air handler, which directs the airflow through the selected vents, and mixes the heated air with fresh outside air to control the output temperature. The air handler uses motors and doors to control the mixture and direction. Check the operation of the doors and replace any that are not functioning. Older vehicles may have vacuum motors to control the doors, so inspect the vacuum lines and replace any that are rotted or missing. Check the body of the air handler for cracks or leaks that may be admitting uncontrolled air. Some vehicles come equipped with a cabin air filter that cleans the return air from the passenger compartment. Check this filter and replace or clean it as necessary, since it will restrict the air circulation through the system if it's dirty.

Low Engine Temperature

A faulty thermostat is the No.1 reason for low engine temperature. Sometimes a thermostat can become stuck open, or open too early. Immerse the thermostat in hot water and check its operation. The thermostat should be fully closed, and start to open at 185 degrees F, and be fully open at 205 degrees F, depending on the rating of your car's thermostat. Replace the thermostat and thermostat seal if it doesn't close fully or opens too early.

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