2000 Deville Service Engine Soon Light

[Justin J]

Checked the codes this morning. ..........
P1540 History only. Nothing current for the AC. The AC was blowing cold before and after I checked the codes this AM in the drive. Now what?

[Ranger]

P1540 - Air Conditioning (A/C) Refrigerant Overpressure - Air Conditioning (A/C) Disabled

My money is on a clogged orifice tube, which would indicate a failing compressor. I think the DTC is going to history after the compressor is disabled (thus no longer current). See if Ewill agrees.

[777ER]

Does anyone know where the overpressure switch is located that is setting off the DIM P1540 code?

It's current the whole time in my '00 Deville and I need to know where the overpressure switch is to change it out.

[submariner409]

On my 2002 it's at the compressor, on the discharge tube, near the compressor clutch electrical connector. The manual says you have to recover the refrigerant, change the sensor, and do an evacuation and recharge.

[777ER]

Originally Posted by submariner409

On my 2002 it's at the compressor, on the discharge tube, near the compressor clutch electrical connector. The manual says you have to recover the refrigerant, change the sensor, and do an evacuation and recharge.

Thanks, it got to be there.
I removed the refrigerant to troubleshoot it and gonna jump the overpressure connection for troubleshooting then get a new switch from the dealer since my bro's shop doesn't have any in the network, he mentioned to me there's 2 overpressure switches listed for the '00 Deville AC system.

Also have to remove the overpressure switch hoping to find a part # on it.

Car has 120,000 miles on it.

[ewill3rd]

If I remember right the high pressure device is a sensor, it will have a voltage reference, power, and ground.
If you "short" it the computer will see high or low voltage and will read as an error.

It should be in the discharge hose near the compressor as sub said.
They used to use a temperature sensor but not sure on 2000. Seems like the cycling switch (low side) and high pressure sensor are all you have on there.

[777ER]

Originally Posted by ewill3rd

If I remember right the high pressure device is a sensor, it will have a voltage reference, power, and ground.
If you "short" it the computer will see high or low voltage and will read as an error.

It should be in the discharge hose near the compressor as sub said.
They used to use a temperature sensor but not sure on 2000. Seems like the cycling switch (low side) and high pressure sensor are all you have on there.

Took it out and no part # was found on it. Not even a brand logo.

Took it to the dealer parts dept to find out it's # 22664320...new one costs $56

A day later, installed it, cleared the code, charged it with r134a and the a/c came back alive and stayed running the whole time....no more P1540 codes.