Expert: autohelp - 9/28/2009

Question
QUESTION: How do you trouble shoot AC pressure sensor?

ANSWER: I need more information.

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QUESTION: On my Dashboard message center it says check Ac Sensor fault, My air conditioner will not turn on. Thsnk you

ANSWER: What is the YEAR of your vehicle ?.

Are you trying to change the freon from R-12 to R-134a ?.

WHICH sensor is causing this problem ?.



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QUESTION: It is a 1991 Cadillac Eldorado. No I am not changing from R-12 to R-134a. I don't know which sensor it is that's why I am asking this question.

Answer
There are TWO pressure sensors a HIGH and a LOW pressure sensor. You can test them with a DIGITAL VOLT/OHM METER or by using the CLIMATE CONTROL PANEL in your vehicle.

You need to unplug the sensor that is giving you problems and measure the OHMS of the switch and let me know what ohms reading you get.