North Ride

I guess I don't understand what the ambient temp update is.
I thought that, when I stated that it was 62 degree F, I was giving you the ambient temperature.

tech2

most gm products and maybe your car...has a sensor that reports the outside ambient temperature to the computer. if this sensor reading is to cold the a/c will not turn on and it will flash the a/c light. the name of this sensor is the ambient temperature sensor.
this sensor, located under the hood, uses an algorithm to compensate for underhood temperatures that may skew its readings. Because of this, the reading is not always live. It updates under certain conditions. One possible cause for the a/c not turning on is.....the ambient temp sensor needs to update...as the old reading was below the temp needed for a/c operation.

North Ride

Ok, this is what I've done.
I replaced the Ambient temp sensor and I did the update with this sensor. The temperature was at 60 degree F., today, and the A/C still doesn't work. Seems like the refrigerant is high enough to run the system but the compressor will not come on. Anything else I can try?

tech2

the proper way to diag this is to check for powertrain and body codes.


Here is some system information:


The following conditions must be met in order for the powertrain control module (PCM) to turn ON the compressor clutch:

• The ambient air temperature is above 4°C (40°F).
• The engine coolant temperature (ECT) is less than 124°C (255°F).
• The A/C pressure is between 241–3034 kPa (35–440 psi).

Once engaged, the compressor clutch will be disengaged for the following conditions:

• The throttle position is 100 percent.
• The A/C pressure is more than 3034 kPa (440 psi).
• The A/C pressure is less than 241 kPa (35 psi).
• The engine coolant temperature (ECT) is more than 124°C (255°F).
• The engine speed is more than 5480 RPM for at least 409 seconds.
• A transmission shift has occurred.
• The PCM detects excessive torque load.
• The PCM detects insufficient idle quality.
• The PCM detects a hard launch condition.
• Outside air temperature is detected to be below 38° F by the OAT sensor if equipped.
• The blower switch is turned OFF.

When the A/C compressor clutch is disengaged for any of these reasons, the A/C indicator LED will flash indicating A/C is not functioning. When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.

North Ride

Okay, here we go,
I took my car to garage to have hoses replaced and asked mechanic to check for codes pertaining to A/C and this is what he gave me.


PO532
A/C refrigerant pressure sensor circuit low voltage.


What could be causing this? Do I need to replace this sensor or is something else causing this?

tech2

when the refrigerant pressure is low the a/c pressure sensor reads low. the system will set this dtc when the psi is less than 1.


Important!!!!!Was the dtc current or history? If its history you can probably disregard it. If its current try this...


if the system was empty from a leak you must find and fix the leak. the filling method you used is not accurate so who knows what charge level is in the car...or if it has leaked out at this point.


the other possible fault is with the sensor circuit. the circuit could have a open, short to grd, 5 volt ref problem or bad sensor.
easy things that you could do are:
unplug the a/c pressure sensor
-key on-verify the 5 volt ref power to the sensor; grey wire
-key off- check the grd wire for less than 10 ohms; blk/white wire


no easy way to check the signal wire without a scan tool. your only option is to ohm check the signal wire from the sensor connector and a unplugged ecm connector.


so if you want my best guess based on your limited testing that you can do...
if your sure the system is charged properly, has 5volt ref and the grd wire is good...try a new pressure sensor...it will probably cost $50.