Heater Blowing Cool Air

There is nothing more frustrating than having a heater blowing cool air with the outside temperatures dropping into the 20’s and 30’s.

To help you find the problem and get that warm air flowing again we need to ask a very important question.

Does your jeep have an automatic temperature control system?

If you are unsure whether your jeep has a automatic temperature control system, you can find this information in your jeeps owners manual. Older jeeps will not have this type of system.

If your answer to this question isno then your jeep has a standard (manual) heater system and the most probable cause would be your heater control valve is not opening. This would be the cause of your heater blowing cool air.

The heater control valve is usually located in one of your heater hoses and controls the amount of air that is sent to the heater core.

The control valve is either controlled by a vacuum line or a lever connected to a cable and both are controlled form levers on your dash.

Depending on way your heater control is operated, check the vacuum hose or control cable to make sure that they are properly connected. Have someone operate the control valve lever to see if the valve is working.

If the valve doesn’t seem to be working properly, replace the valve or take your jeep to a qualified service professional.

Yes, I have one of those fancy heater systems

The automatic temperature control system is a fairly complex system and usually requires a qualified service professional to diagnose and fix any problems.

Your vehicles onboard computer controls the system to maintain a constant temperature inside the passenger compartment.

The system probably has a bad ambient air sensor or a problem with the blend door and would be the cause of your heater blowing cool air.

A bad ambient air sensor will send inaccurate information to the computer and could cause the blend door to not open enough to allow enough air to flow through the system.

If the problem is with the blend door, it’s possible that it has become bound or the control mechanism has failed.

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