The most common fix to the problem of your Subaru’s air conditioning not blowing cold anymore is a A/C recharge.
The rubber O-rings that act as a seal in the A/C lines can bad and allow for Freon to leak out and empty the A/C system, also causing a lack of cold air.
A proper recharge consists of draining the existing Freon from the A/C lines, replacing the O-rings if necessary, refilling the freon or ‘recharging’, and then using a state of the art Freon detector to locate any leaks in need of repair.
Once charged, your Subaru’s A/C should provide you with years of cool comfort on your daily commute.