Hi there! I've got a 2017 Nissan Altima SV with a 2.4 L 4-Cylinder and about 97,000 miles. I bought it 6 months ago and the A/C compressor died the same day I bought it (bought from a rather large dealership) I let my dad use it as his daily driver to work, and he's told me that the a/c doesn't blow very cold even when it's on max. We live in Houston so the summers are pretty warm as I'm sure you know. I bought one of those a/c refrigerant cans with the pressure gauge from the auto parts store and it wasn't much help. Could there possibly be a leak coming from the schrader valve? I noticed when I picked the car back up after the repairs were done that there were no caps on the high pressure port or the low pressure side. Other than that the car runs and drives fine, other than the high rev counter when accelerating due to the CVT trans. Thanks!
I bought one of those a/c refrigerant cans with the pressure gauge from the auto parts store and it wasn't much help.
That was a mistake. Those things are typically useless and can damage or destroy your AC system if they contain sealers. The cheap low-side gauge is virtually worthless for diagnostic purposes. Modern AC systems require the correct refrigerant charge within a couple of ounces and you are unlikely to get there with one of those stupid things. The only way to know you have the correct amount of refrigerant is to evacuate the system and install the factory-specified amount by weight.
The service valves would be a common leak point. You can check for leaks there easily with some soapy water. You can also use UV dye or an electronic detector to find leaks.
https://www.youtube.com/watch?v=_IBFLMYZEzI
https://www.youtube.com/watch?v=0HCSsv3uYfM
