my air conditioner compressor doesn't work and it seems that it should have lasted much longer. What do you think about this?

Hello, Four to five years is not great, but I have seen much worse. In TN, the load on an air conditioner is nothing but extreme since the humidity and heat get out of hand in the summer months. However, I would still like it to last a little longer. Most times, when a technician says they cannot add refrigerant to the system, it is due to a leak. This will cause the compressor to cease running when the low pressure sensor for the A/C recognizes the situation. I would look for clarity before allowing a repair. If you are the original owner, you may still have warranty.