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How Does The Evaporator Core Work?


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What does it mean that my dash door to the evaporator core is not opening? Where is the door located? The shop supposedly charged my system and told me that the compressor is working fine but that they can't access the evaporator core. I understand that the core chooses between heating and cooling but I don't know the specifics of how it works and what my problem may be? Thanks for any advice.

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The blend door determines how hot or cold the air coming out of the system will be. ALL system airflow comes through the A/C evaporator to be cooled first, and then a portion, or all, is routed through the heater core and then remixed with the unheated portion to get the proper air temperature outflow.

If you open the hood and look near the top center of the firewall you will see the hot water control valve. The servomotor that moves the blend door inside the car has a cable attached which at the same time controls the hot water valve. If you warm the engine and with the A/C and then select Max cold, the lowest temoperature setting, the cable should move the water valve to its fully closed position. Move the temperature selection to max hot and the hot water valve should be fully opened.

In max hot ALL of the system airflow goes through the heater core and at max cold none will.

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