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Air conditioner I have a 2001 cadillac deville. Error code p1540 (air conditioner over pressure A/C disabled). I have never added freon the the vehicle, and Ive owned the car for 2 years. The compressor will not engage, could it be the orifice tube? or a bad sensor? I checked to low side pressure and it was 45 @ 90 degree temp.

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Added freon - air conditioner won't come on

there are 2 pressure switches in the system 1 stops the ac compressor if there is not enough gas in the system and the other stops the compressor if there is too much gas . Next if there is a problem in the TX valve ( blocked orifice) then the head pressure will be too high and the compressor will not work. Next if you have not had the system checked for leaks ( why did you put more gas in ) then it has probably already been pumped out through the hole.. While you consider it a saving to do your own in the long run it is more expensive not to use an accredited auto air conditioner shop.

Mar 24, 2014 | 1999 Cadillac DeVille

2 Answers

Why my ac in my cadillac deville 1996 blows hot air?

If your low on freon then the A/C wont come on? for a 1996 you will need to get it serviced if you havent its normal to loose 10% freon a year,

May 06, 2011 | 1996 Cadillac DeVille

1 Answer

My a/c is inoperative, clutch will not engage in normal operation. i am t getting two codes p1540 refrigerant overpressure/ac compressor disabled and u1000 class 2 communication malfunction. i have...

The wire that you found hanging probably goes to the a/c pressure sensor. Basically, this sensor will shut the compressor down if your system builds up excessive pressure. This would not affect the fans just the compressor. I hope this helps you figure this out.

Aug 16, 2010 | 2002 Cadillac Deville

3 Answers

1999 cadillac deville a/c off low refrig error

I had the same problem. The mechanic could not get the compressor to take in new freon. It has to do with the car's memory. You have to reset it by disconnecting the hot wire from the battery which for thirty seconds. This resets the cars internal memory, so it won't remember that it's out of freon. Reconnect it turn on the car and turn on the air the compressor will start.

Apr 26, 2010 | 1999 Cadillac DeVille

1 Answer


Did you just fill the freon? Have you tried unhooking the battery to reset the system?

Apr 03, 2010 | 2001 Cadillac DeVille

3 Answers

How do I reset the computer after adding freon to my air conditioner on my 1995 Cadillac Concours

Simply Disconnect the Negative Battery cable for 1 Minute and this Will RESET it for you , If there is STILL a Problem it WILL COME BACK on.

Sep 27, 2009 | 1995 Cadillac DeVille

1 Answer

1996 cadillac deville compressor stopped, new compressor and dryer put on, but unit will not accept freon. Please help.

Sometimes, you have to start the vehicle, turn on the AC (Hi setting), and jump across (bypass) the low side pressure switch - to allow the compressor to start running and draw the freon in through the low side - make sure your fittings are correct and otherwise - Did you pull a vacuum on the system before you attempted to add refrigerant? I would highly recommend it - removes air and moisture....

Aug 22, 2009 | 1996 Cadillac DeVille

1 Answer

Location for adding freon

add freon to low pressure side . low pressure side is large line with small fitting. high pressure line has a large fitting.

Apr 04, 2009 | 1999 Cadillac DeVille

1 Answer

1996 cadilac air conditioner problem

Try unhooking the battery. When caddies see they are low on freon or have a bad pressure switch, they set a code and lock out the compressor function. Unhooking the battery for a minute should reset this.

Mar 25, 2009 | 1996 Cadillac DeVille

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