2010 Aveo AC Compressor Will Not Turn On

[vettepwr]

We have a 2010 Aveo here at our shop and we are trying to solve a problem the customer is having with the AC.

When we use our scantool to look at the datastream we can see that the IPC shows that the AC Switch works, however when the Ac switch is on the PID " AC Request" says Off. When we look at the ECM datastream there are several PID's that don't look right. They are:
AC Compressor - Not Allowed
AC Requestignal - No
AC High Pressure Sensor - 0 PSI
AC High Pressure Sensor - 0 Volts
AC Relay Command - Off
AC Relay CKT Short to Power TST Status - Fault
AC Relay CKT Short to Ground TST Status - Fault
AC Relay CKT Open TST Status - Fault
AC Pressure Disable - No

The first thing I did was check the AC pressure sensor. It seems to be working just fine, It has a good 5V VREF supply to it and with the AC off the signal wire shows about 1v , when I bypass the ac relay and manually turn the compressor on the voltage from the pressure sensor goes up. Because the datastream shows the pressure sensor @ 0v and 0PSI I then Ohm tested all 3 wires from the pressure sensor to the ECM. They were all ok. When I backprobed the ECM connector on the Pin for the Pressure sensor signal I read the same voltage I got checking at the sensor. I even tested the wire that runs from the AC Relay to the ECM, it was good as well. After this I assumed the ECM was bad, with the sensor being good and the wiring testing ok, there was no reason for the ECM to be showing 0V and 0 PSI for the sensor reading.

Customer opted for a used ECM which we installed and reprogrammed. The new ECM changed nothing. We are out of ideas at this point. What doesn't make sense is that with the AC Pressure sensor reading 0v-0psi there should be a DTC set for AC Pressure sensor Low Voltage but there isnt. The AC Relay CKT Test Status PIDs showing all faults dont make sense either as there are not faults detected in the wiring, and yes we did try swapping the relay out.

If anyone has any ideas please post.

[2010AveoLT]

We have a 2010 Aveo here at our shop and we are trying to solve a problem the customer is having with the AC.

When we use our scantool to look at the datastream we can see that the IPC shows that the AC Switch works, however when the Ac switch is on the PID " AC Request" says Off. When we look at the ECM datastream there are several PID's that don't look right. They are:
AC Compressor - Not Allowed
AC Requestignal - No
AC High Pressure Sensor - 0 PSI
AC High Pressure Sensor - 0 Volts
AC Relay Command - Off
AC Relay CKT Short to Power TST Status - Fault
AC Relay CKT Short to Ground TST Status - Fault
AC Relay CKT Open TST Status - Fault
AC Pressure Disable - No

The first thing I did was check the AC pressure sensor. It seems to be working just fine, It has a good 5V VREF supply to it and with the AC off the signal wire shows about 1v , when I bypass the ac relay and manually turn the compressor on the voltage from the pressure sensor goes up. Because the datastream shows the pressure sensor @ 0v and 0PSI I then Ohm tested all 3 wires from the pressure sensor to the ECM. They were all ok. When I backprobed the ECM connector on the Pin for the Pressure sensor signal I read the same voltage I got checking at the sensor. I even tested the wire that runs from the AC Relay to the ECM, it was good as well. After this I assumed the ECM was bad, with the sensor being good and the wiring testing ok, there was no reason for the ECM to be showing 0V and 0 PSI for the sensor reading.

Customer opted for a used ECM which we installed and reprogrammed. The new ECM changed nothing. We are out of ideas at this point. What doesn't make sense is that with the AC Pressure sensor reading 0v-0psi there should be a DTC set for AC Pressure sensor Low Voltage but there isnt. The AC Relay CKT Test Status PIDs showing all faults dont make sense either as there are not faults detected in the wiring, and yes we did try swapping the relay out.

If anyone has any ideas please post.

this may sound like a stupid question, but did you verify that the A/C system has a charge in it? because if the High pressure switch reading is actually correct, the ECM will not allow the compressor relay to activate to prevent damage to the A/C system.