I wanted to test the efficiency of my A/C so I ran a simple A/C cooling temperature test on my 06 LS430. Vehicle has 90K miles well maintained and running well.

With the outdoor temperature running at 97 degrees F I inserted a 6" temperature probe into the driver side air vent, set the temperature at Max Cold and ran the car for 15-20 minutes. The coldest temperature point I got was a level 55 degrees F.

This sounds high to me anyone have thoughts or feedback?

 

Yes, that sounds high. My guess is it's a little low on refrigerant, but it could be a lot of things. Cleaning the condensor can also make a difference.

As a comparison, my car with around 100 degrees outside can get as low as 39 degrees from the center vents, but that's with the car moving.

I tested it because it seemed warm on the inside, but it turns out it has more to do with my black leather upholestery.

 

I was curious and ran the test again but this time the vehicle was on the open highway and not in stop and go city traffic. The temperature leveled off at 43 degrees much better than before but still 10% less efficient BradTank. I guess you are probably right that I am low on refrigerant.

I know that a few years ago my A/C was amazing and the best I've ever experienced and guessing that the compressor was cranking out air in the low to mid 30s.

Does anyone know the optimal spec temperature range assuming all A/C components and system is functioning properly?