I have a 2005 Escalade. On my scanner ambient temp sensor reads 50. Wire 1 is shorted to ground either in the harness or A\C controller. Will this make the ECM not energize the relay?
You would need to find the short first before replacing the sensor, the short may be causing the problem.
There are other reasons the compressor is not engaging. The following conditions must be met in order for the A/C compressor clutch to turn on:
Ambient air temperature above 4°C (40°F)
A/C low pressure switch signal circuit is grounded
A/C refrigerant pressure sensor parameter is less than 2957 kPa (429 psi)
PCM receives an A/C request from the HVAC control module
Engine coolant temperature (ECT) is less than 121°C (250°F)
The engine rpm is more than 550 rpm
The throttle position is less than 100%
Put a set of A/C gauges on the system and check the pressures. You may just be low on refrigerant.
Is your scanner a professional scan tool or just a code reader? A code reader can not check electric A/C parameters. Let me know when you can, we can diagnosis the problem further if needed.