141k miles
Reasonably competent and conscientious shade-tree mechanic here. I get that AC troubleshooting and repair are best left to techs certified in such. But I don't believe I'm quite ready for their services just yet. I'm trying to determine if the AC problem I have with this car is within the scope of my ability. That said...
A few days ago, the otherwise reliable AC in our Azera stopped working. When the AC console controls are activated the tach shows immediate engine idle-up yet NO cold air comes out the vents. Under the hood, I can see the compressor clutch does NOT activate. The AC fuse tests ok. AC relay tests ok; however, I do NOT hear/feel the AC relay activate... may indicate the ECU isn't sending 12v to the relay (more on this below). I climbed under the engine and disconnected the clutch coil connector, blasted the contacts with air & WD-40, then reconnected and tested--still no clutch--I still need to apply 12v directly to the coil to test that part.
Static system pressures are dead-equal at ambient temp; no detected pressure drop after being connected for 48hrs (see image below). Since the clutch will not engage, I cannot get dynamic system pressures. From what I've read here and elsewhere, equal static pressure @ ~100lbs between both gauges is normal.
The ECU controls the AC relay. (I presume the RPM bump when I turn on the AC indicates the ECU is working correctly.) The service manual lists two AC system sensors that feed into the ECU--the "evaporator temperature sensor" and the "AC pressure transducer". Failure of either may prevent the AC relay from closing (via the ECU), so I need to test these components.
I have the service manual in front of me, but surprisingly it doesn't provide a t'shooting flowchart for the AC system. I'm open to advice for appropriate "next" procedures.
- 20170811_110404.jpg (189.36 KiB) Viewed 8702 times
- AC_pressure_transducer.jpg (143.6 KiB) Viewed 8697 times
- evaporator_temperature_sensor.jpg (152.19 KiB) Viewed 8697 times
