The AC on my 07 trailblazer ls with the 4.2 inline 6 has stopped working. The compressor clutch will not engage. I have pulled the ac relay out and used a jumper to make the clutch engage and it does then I checked the relay and it is working correctly as well. I have a relative that is a mechanic that looked at it for me he hooked his computer to it and found the ambient air temperature sensor reading 32 degrees on an 80 degree day. So the conclusion was made that the sensor is bad. But I can't find the sensor. The car was recked about six months after I bought it new in 07. No major damage to the front end just the plastic front bumper cover was replaced nothing above the bumper in the grill or head lights. But my first thought was this sensor that is supposed to be located on the driver side on top of the radiator behind the grill was probably taken loose and moved when the body repair was made. So I find a friend that that has an 05 trailblazer ls il 6 so I can trace the wiring harness and start looking from the other end and it doesn't have one either at least not where everything and everyone is saying to look for it. Neither on of these two vehicles came from the factory option of having a digital read out of the outside air temperature. So after all this back story my question is does my trailblazer use an ambient temp sensor or do I have a computer problem? Any help would be appreciated.

 

Had that issue come up on my 2015 Malibu a couple weeks back. Ambient temp sensor was on drivers side behind grille. Got lucky and pulled the wires out, cleaned it up, and applied some dielectric grease to the connection. Works like a charm again and cost nothing but some time, as I use dielectric grease on everything, since I used to own a Jeep CJ-5 and deep water crossings were commonplace. Don't know if this is your issue but the sensor has to be somewhere away from the radiator and A/C condenser in order to obtain a proper ambient temperature reading.

 

Thanks for the reply I'm going to keep looking for the sensor but no luck yet

 

You may not have one. If you did have one, it would still be in the general area where it's supposed to be. The connector off the harness is only a few inches long.

Do you have automatic temperature control or manual temperature control?

Even if you have automatic temperature control, the A/C should still work when you manually select your temperature and fan.

I'm thinking something else may be wrong.

How is the refrigerant pressure when you manually engage the clutch?

Is there too much or too little refrigerant in the system?

When you first start the car, does the A/C compressor engage any?

Is the cooling fan or fans running?

If the cooling fan that cools the condensing coil is not working, the refrigerant won't condense back to a liquid and the pressure switch will keep the compressor from turning on.

Does it blow cold air when you manually engage the clutch?

 

Found this location, but its for a 2002 so I dont know if Chevy moved the sensor elsewhere for 2007.