Question about Cadillac DeVille

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I have a 1999 cadellic deville and at first the panel readout showed low frefrigrant. I took it to Climatic air in Tyler and they replaced the compressor. They said it was ready and I drove away and within 15 minutes it showed the same Low Freg reading again and stopped cooling. Well after the 5th trip back they replaced the two sencors and it still would go to Low Freg. I noticed that everytime I pulled the power to the battery and reconnected...the cold air would blow for about 15-20 minutes then show low freg each time and air would shut off. Where is the computer located on the car that receives the message from the AC sencors and is responsible for turning the low Freg indicater on and shutting off the AC. I figured there might be a loose connection to that computer? Where is this located and what are your thoughts from someone who is an expert in Cadellic AC systems? Thanks, Sans

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  • sanshawkins Jul 16, 2010

    Your help was super and I will use the service again. My answer came in a speedy manor and he answered every concern that I had addressed.
    Thanks, Sans from Tyler, Texas


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Your A/C system is equipped with sensors for Hi and Low pressure, they are the ones that send the signal to the computer. And for what you are saying, are the two sensors that were replaced.

I beleive you are right, there is a loose connection or broken wire on the low pressure sensor circuit. Since you know that the gas level is fine, you can do the following test;

Find the fatter hose coming from the compressor, it is the Low Pressure or Succion side hose, it goes from the compressor to the firewall, there should be an aluminum can called filter/receiver/dryer in between, on top of it or somwhere close you'll se an electrical plug, it is connected to the low pressure switch or sensor. unplugg it and use a piece of wire to jump the two wires together,(the sensor will be left disconnected) this will send the computer a signal that the pressure is fine and will keep the compressor running. Test it for a cuple of days and then fix the problem.

Good Luck!!

Posted on Jul 14, 2010

  • sanshawkins Jul 15, 2010

    Thanks for the sencor bypass info. Could you tell me where the computer is located in case the wire that I am shorting is bad to the computer. The computer location was in my question inquiry.

    Thanks Bunches, Sans

  • Rene J Solis Jul 15, 2010

    The computer or ECC is located under dash, pasenger side.

    As long as you know the system is full of freon gas, you don't have to worry about bypassing the low pressure switch. Is the compressor kiking in now?? Is it staying on and cooling?? It should!!


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