no power to a/c system?

[arthurpendragon]

Yesterday I thought I had to add some gas to my ac on a '02 with the 3.5.  Nope.

There is no power to the low pressure cutoff switch (atop the receiver-dryer).  Checking further,  I tried the relay.  The horn relay sits right next to it and they both have the same number.  I switched them - horn still works.  Looked at all the fuses that said AC in the legend....

Anybody been here, and found this?  Please?

I did make some progress - lol.  Found the coil on the relay for the air pump open.  Shorted the plug and heard the motor start.  Rock auto has a ac delco for $18.  Local store wanted $50...

[sempar]

Arthur,

The pressure sensor gets a 5V reference from the PCM on the grey wire, returning to the PCM on the black wire. Power for the sensor is 5V from the PCM on the red/black wire. Do you have 5v from the red black with ign. on, ac engaged? IF not, suspect a bad wire, connector, or PCM. If so, check for 5V at the grey wire and check the return to the PCM on the black. The return will be lower than 5V depending on ac line pressure, but you should still see voltage on this wire to the PCM.

John

[arthurpendragon]

Jun 1, 2019 13:05:14 GMT -6 sempar said:

Arthur,

The pressure sensor gets a 5V reference from the PCM on the grey wire, returning to the PCM on the black wire. Power for the sensor is 5V from the PCM on the red/black wire. Do you have 5v from the red black with ign. on, ac engaged? IF not, suspect a bad wire, connector, or PCM. If so, check for 5V at the grey wire and check the return to the PCM on the black. The return will be lower than 5V depending on ac line pressure, but you should still see voltage on this wire to the PCM.

John

The sensor I'm talking about sits atop the receiver-dryer.  Low pressure cutoff, I believe...

[sempar]

Arthur,

Yep, that's the one. No other pressure sensor in the a/c compressor circuit.

John