a/c refrigerant pressure sensor

Hi everyone.
Somebody could help me finding the function of the three wire connect to the a/c refrigerant pressure sensor on my 3500 Sprinter 2007. Is there a 12 volt present do I get a reading from an ohmeter between those wire from the sensor in or out circuit. A Dodge dealer replace my a/c compressor in fall last year. Since that time I never had to used it. Now gest what it not working.
Thanks in advance.
Francois

The wiring and the connection into the back of the compressor are for the swash plate control of the compressor.

This feature is briefly to control compressor displacement and provides variable pressure demand when the HVAC controller head calls for cooling.
The figures are usually read by using a scanner.

There will be a 12v feed, a ground and a reference signal.

Since the system was working and now doesn't, why not at first check to see how much refrigerant is in the system? Since it may have leaked out or be significantly low.

The best way to check this is have a shop remove the refrigerant with a re-cycle machine that weighs the removed refrigerant. Then have the correct amount re-installed and then try the system.

This base lines the mechanical side before moving into the electronic control area.
This diagnostic activity definitely requires a sophisticated scanner capable of reading the HVAC system.
Dennis
Mechanic

First: Thanks Dennis for your answer.
The garage have replaced the compressor. On a two wire connector going to the compressor there is only one hook to it. When checking it with the a/c on there is a 12v and with a/c rest botton on the reading is about 7 volts. I dont know if the clucth is engage. What I thing it is not engage because the ground wire coming from the computer is connected to the frame of the compressor like before the replacement. I will try to move it to the second position of the connector. I imaging the clucth coil is isolated from ground with this new compressor. I will post the result.
Regardless of the clutch on the pressure sensor I found no voltage when a/c is on. You mention 12v, ground and a reference signal is this on the pressure sensor.
To respond at the question the refrigerant give 7 bars both side am, I right to assume it is correct.
Thanks
François

Where I am with my problem. a/c on, compressor connector removed between red and black wire I have 13.9 volts. Putting back the connector the 13.9 volts dissapear. I assume there are an another condition faulty so the ecm remove the 13-9 volts. Now at the refrigerant pressure sensor (3 wires) a/c off I have ground, 5 volts, and 0,99 volts. with a/c on I have the same reading. Is this 0.99 volts is a normal output for a signal wire?
Someone could answer me if normal or bad.
My next move: I will try to find the location of the evaporator temperature sensor to test is output.
According from my finding there are two other sensor involve in the decision of the ecm to shutt down the compressor. The outside temperature sensor and the inside temperature sensor I found there location I will check if they seem o.k.
Any help will be appreciate.
Thanks
By the way I have 100 psi on the low pressure reading side and the same on the high pressure side. If the compressor is shutt down is those reading are acceptable?

TangoSalsa said:

Where I am with my problem. a/c on, compressor connector removed between red and black wire I have 13.9 volts. Putting back the connector the 13.9 volts dissapear. I assume there are an another condition faulty so the ecm remove the 13-9 volts. Now at the refrigerant pressure sensor (3 wires) a/c off I have ground, 5 volts, and 0,99 volts. with a/c on I have the same reading. Is this 0.99 volts is a normal output for a signal wire?
Someone could answer me if normal or bad.
My next move: I will try to find the location of the evaporator temperature sensor to test is output.
According from my finding there are two other sensor involve in the decision of the ecm to shutt down the compressor. The outside temperature sensor and the inside temperature sensor I found there location I will check if they seem o.k.
Any help will be appreciate.
Thanks
By the way I have 100 psi on the low pressure reading side and the same on the high pressure side. If the compressor is shutt down is those reading are acceptable?

Click to expand...

Did you solve your problem? I have a similar problem and would like to hear your solution.

https://sprinter-source.com/forum/showthread.php?p=569623#post569623


see the attached link for system overview... part 3 page 59.

One year later a/c still not working. Visit to Mercedes garage they told me the compressor is short to ground error 9601 and a new one will be 2600$. Consultation cost 453$. Bull****. Because if I put 12 volts and a resistor of 20 ohms in serie with the compressor valve positive side and ground I have lot of cold air. Conclusion without the computer the compressor and gas are working good. After checking ambiant temp, coolant temp, a/c pressure sensor, aux fan and relay all good my compressor was still on guaranty so I exchange it again no cost with the dryer and the expansion valve. Still no a/c.
My founding: unplug the connector to the compressor, engine on, a/c off, reading between positive pin and ground 3.51 volt now a/c on voltage go up to around 12 volts and down around 10 volts trying to open the compressor valve no error reading. Whit my old compressor Denso original (bearing problem)on the ground I plug the connector to it voltage stay on and still no error.
On the truck the compressor is a Four seasons 158376 install by the Dodge garage last time and change again this year if I plug the wire to the valve, voltage goes to zero and no cold air. Error 9601 appear.
My question is: Is there somebody using a 158376 on their Sprinter I beleive the are not compatible with the computer event the seller say yes.
Resistance off the valve on the Denso 10.2 ohms and on the 158376 resistance 11.7 ohms.
Thanks for your attention.