A/C blows warm air when driving

Hi and thanks for using 2CarPros.com.

This could be the result of low Freon in the system, a partially plugged system, a blend air door in the vehicle not functioning properly.

Since it never gets more than "cool" before driving, I would start by checking both the high and low side compressor pressures. Here is a link that describes how the system is properly recharged and discusses pressures from both sides of the compressor:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Once you determine the pressures, let me know the following. What both the low and high side pressures are and I will need to know the outside temperature when tested. Ambient temperatures (outside temperature) will play a big role in what the pressure should be under different conditions.

Do this first and let me know what you find.

Thanks,
Joe